Banner
Current IssueEditorial BoardOnline First ArticlesArchive
Current IssueEditorial BoardOnline First ArticlesArchive

Review Article

Sulfur Nutrition in Plant Growth Promotion by Sulfur Oxidizing Bacteria: A Review

K
K. Sowmya1,*
S
S.L. Sivapriya2
1Department of Agricultural Microbiology, School of Agricultural Sciences, Bharath Institute of Higher Education and Research, Tambaram, Chennai-600 001, Tamil Nadu, India.
2Department of Science, Janani Public School, Bangalore-560 001, Karnataka, India.

ABSTRACT

Since sulfur is a vital nutrient for plant development, a lack of sulfur can result in significant reductions in crop yield. Sulfur deficiency often results in the addition of sulfur fertilizers to soil, typically in reduced forms like elemental sulfur. However, the reduced sulfur fertilizers must be converted to sulfate by microbes before they can be utilized by plants. The purpose of this review article is to explore the natural occurrence of sulfur in soil, the overall conversions that sulfur undergoes, its function in plant physiology, the variety and microbial oxidation of different reduced sulfur forms, it can boost plant growth by measuring sulfur oxidation in soil and modifying factors that influence sulfur oxidation. 

INTRODUCTION

Besides nitrogen, phosphorus and potassium, sulfur (S) is becoming recognized as an   essential nutrient for plants. All compounds containing reduced sulfur are composed of cysteine and methionine, which form the building blocks of cysteine and methionine (Sharma et al., 2022). Sulfur is crucial for the survival of both plants and animals. The first documented case of sulfur deficiency was reported in 1933, despite being essential to plants in quantities like phosphorus. The initial observation of sulfur deficiency in wetland rice occurred in 1938. Both dryland crops and wetland rice have been identified as being negatively affected by sulfur deficiency over the past decade. Tropical regions are notorious for sulfur deficiencies arising in different types of andosols, vertisols, alfisols, ultisols and oxysols. Sulfur deficiency has been documented in wetland rice from Bangladesh, Burma, India, Indonesia, Japan, the Philippines and Sri Lanka. Reports indicate that 23 different crops in 40 tropical nations have shown positive responses to sulfur. Low sulfur fertilizer applications have increased, organic manure use has fallen, intensive cropping practices have declined and atmospheric pollution has decreased (Camberato and Casteel, 2017). Sulfur fertilizers, typically in reduced form like elemental sulfur, are used to resolve sulfur deficiencies in soils. The application of sulfur oxidizers accelerates the natural oxidation process of sulfur and hastens the production of sulfates, thus making them accessible to plants during crucial growth phases, which ultimately leads to higher crop yields (Valle et al., 2019; Skwierawska et al., 2016; Anandham et al., 2007; 2008a; Stamford et al., 2013; Stamford et al., 2015). A variety of microorganisms, including prokaryotes and green sulfur bacteria, have been identified that either obligately or facultatively use sulfur compounds as electron donors and oxidize these compounds into sulfate. Sulfur oxidizing bacteria such as Thiooxidans, Pseudaminobacter salicylatoxidans and Paracoccus are recommended as inoculants for different rice-growing ecosystems. Therefore, this study has isolated microorganisms from several ecological environments, but currently, there is no appropriate sulfur bio-inoculant available (Rameez et al., 2021). This review article discusses the natural occurrence of sulfur in soil, the general transformations of S, the physiological role of sulfur in plants, the diversity and microbiological oxidation of various forms of reduced S, methodologies for quantifying sulfur oxidation in soil, factors that influence S oxidation in soil and the implications of using sulfur-oxidizing bacteria (SOB) as plant growth promoters in the agro-ecosystem.
 
Sulfur in soil 
 
Among the 105 elements that compose the Earth’s crust, sulfur is found in a concentration of approximately 0.03%, ranking as the 17th most prevalent element. The elemental sulfur found in soil is primarily the mineral sulfides, sulfates, hydrogen sulfides and organic sulfur compounds. Minerals such as pyrite (FeS2) provide most of the sulfur in soils. Soil redox potential is closely linked to the oxidation state of sulfur in pyrite during weathering and soil formation. Reactions involving the oxidation and reduction of sulfur occur quite readily, leading to a wide variety of reactions that sulfur experiences in the soil. Soil sulfur content is generally   influenced by three factors: (1) organic matter, (2) clay percentages and clay minerals, (3) levels of iron and aluminum oxides.

The organic sulfur content in soil rises with increased humus levels. Peat and marsh soils have a high concentration of organic sulfur. In the South Pacific, the total sulfur content tends to be lower in soils with minimal organic matter (Germida et al., 2021). Organic matter and sulfur deficiency are common in tropical soils due to weathering and leaching. In southern China, there is a positive correlation between total sulfur and the percentage of clay. Soils with iron and aluminum oxides retain sulfur longer than those with coarse textures, partly because they contain more organic matter (Das et al., 2022).
 
Fractions of soil sulfur
 
Plant availability of sulfur(S) is not directly related to soil sulfur(S) levels. In soil, sulfur exists in several forms, so its availability to plants depends on how it is transformed and how it interacts with other sulfur fractions (Fig 1). (Germida et al., 2021).

Fig 1: General distribution of various sulfur fractions present in soils (Germida et al., 2021).


 
Organic sulfur compounds
 
Like organic matter, organic sulfur(S) has a decreasing distribution in soil profiles as depth increases. There are three kinds of soil organic S: cation -bonded sulfide, non - cation- bonded sulfide and humus sulfide. Generally, humid and semiarid soils have large amounts of C-bonded organic S. Isolating this fraction is challenging due to the significant transformations that S-containing compounds undergo. In soil, trace amounts of sulfur can be found despite the fact that sulfur is only found in small amounts in amino acids (Kodavali and Khurana, 2022).

Sulfate polysaccharides, like non-carbon-bonded sulfur, are thought to be present in many forms, including unidentified ester sulfates. A small portion of organic sulfur is found within soil biomass. However, the sulfur content in microbial tissue is highly reactive and plays a key role in the turnover of sulfur, impacting its availability to plants (Stellhorn et al., 2022; Ranadev et al., 2023).
 
Inorganic S
 
In soil, inorganic sulfur predominantly exists as sulfate. When oxygen is lacking, sulfur appears as its reduced form. Plants obtain sulfur through the soil’s liquid phase. A significant portion of sulfur in calcareous and saline soils is found as gypsum (CaSO4·2H2O). The solid phase of sulfur consists of sulfate retained in an adsorbed state in arid areas, such as CaSO4, MgSO4 and Na2SO4. Iron oxide and aluminum oxide can adhere to sulfate. This sorption primarily occurs through ion exchange facilitated by the charges present on clay minerals and oxides, with the process becoming more pronounced as soil pH decreases (Table 1) (Narayan et al., 2023).

Table 1: Inorganic forms of sulfur in soil (Bouranis 2020).


 
Plant sulfur and Its physiological role
 
Sulfur compounds have a wide range of physiological functions. Two perspectives can be taken when looking at sulfur’s function: Directly within compounds and indirectly at the level of influencing nutrient synthesis. APS (adenosine - 5' phosphosulfate) and PAPS (3' – phosphoad-enosine - 5' phosphosulfate) are two of the primary sources of sulfur for crop plants. Sulfate serves as the main source of sulfur for crop plants (Fujita and Uesaka, 2022). This strongly implies that sulfur plays a role in the synthesis of chlorophyll. Ferredoxin is categorized as an iron-sulfur enzyme, which lacks a cofactor but typically has equal amounts of iron and sulfur atoms in a specific unstable form that can break down in the presence of acid. In the reduction of nitrogen, NADPH passes on reducing equivalents to ferredoxin, an iron-sulfur protein. Further studies have demonstrated sulfur’s role in the TCA cycle and glycolysis (Tabak et al., 2020).

Sulfur has also been recognized as an essential factor in the synthesis of flavonoids and carotenoids. Additionally, sulfur is crucial for the synthesis of polyamines. The biochemical roles of naturally occurring polyamines include regulating the physical and chemical characteristics of membranes, influencing the structure and function of nucleic acids, modulating enzyme activities and overseeing molecular synthesis (Slocum and Flores, 2024).

Isothiocyanates possess antibacterial and antifungal characteristics as well. Brassica species can prevent the infection of the mildew pathogen Peronospora parasitica through the enzyme-mediated production of allyliso thiocyanate from sinigrin following tissue injury (Velu et al., 2018). In pea plants, a reduced level of sulfur nutrition led to decreased levels of nitrogen, silicon, iron, calcium, magnesium, sulfur and crude ash content, while phosphorus and aluminum contents in both shoot and root tissues increased (Shah et al., 2022). When sulfur and zinc are applied, the presence of one nutrient tends to lower the concentration of the other in the shoots. The interaction between sulfur and zinc likely occurs at absorption sites as well as within the plants themselves (Noman et al., 2020).

Allylisothiocyanate is the sharp and pungent compound found in mustard, which people consume in small quantities as a condiment. This isothiocyanate also serves as the primary flavor component in cabbage and other cruciferous vegetables (Harborne, 2014). Typically, local varieties of horseradish, both wild and cultivated, tend to be more pungent than imported types. Increasing sulfur levels led to a rise in allylisothiocyanate during decay, thereby enhancing its pungency. The allylsulfide content of Korean soil was positively correlated with sulfur availability (r=0.723, n=15, p=0.01) (Park et al., 2024).
 
Sulfur effects on crops
 
The growth of legume plants is adversely affected when soil levels of phosphorus and sulfur fall below critical threshold levels (Chaudhary et al., 2022). Compared to controls, elemental sulfur increased groundnut oil content by 5%, nodule biomass, pod yield, shoot length and dry matter while reducing chlorosis (Noman et al., 2020; Balagangathar et al., 2024). Sulfur increased the rate at which carbohydrates were converted into oil, resulting in more oil and yield per molecule (Singh et al., 2010). The oil content of sesame increased by 3.2% with a sulfur application of 50 kg per hectare (Assefa et al., 2021). Adding sulfur to mustard increased its oil content and seed yield (Sharma et al., 2022). Soybean leaf area, dry biomass, pod count and 100 seed weight were improved with an application of 30 kg sulfur per hectare (Khan et al., 2020). Wheat yield increases by 2.19 quintals per hectare due to an increase of 30 kg S per hectare, as well as an improvement of nitrogen, phosphorus and potassium absorption (Singh et al., 2020). Blackgram yield-related traits and overall yield were significantly enhanced by 30 kg of sulfur per hectare (Ramamoorthy and Ariraman, 2023). A micronized sulfur application increased wheat yield by 36% and sulfur uptake by 164%, according to Kulczycki, (2021). Rice, maize, field beans, wheat, cotton, sorghum and sunflower all grew better after sulfur application, according to Zenda et al., (2021).
 
Deficiency symptoms
 
Sulfur, which is a part of nitrate reductase, plays a crucial role in transforming nitrate into organic nitrogen. Therefore, a deficiency in sulfur disrupts nitrogen metabolism, accounting for the similarities in symptoms between sulfur and nitrogen deficiencies in various crops. Nevertheless, the symptoms are typically mild and not restricted to the older leaves. The appearance of sulfur deficiency is characterized by a light green hue affecting the entire plant. Legumes, particularly alfalfa, have a significant demand for sulfur, making them the first to exhibit signs of deficiency. In corn, sulfur deficiency can sometimes mimic other nutrient shortages like manganese or magnesium, leading to interveinal chlorosis; the upper leaves are often stripped, with veins appearing darker green than the surrounding tissues. To correct sulfur deficiency in crops, the application of sulfur-containing fertilizers is generally recommended (Table 2) (Bouranis, 2020).

​

Table 2: Fertilizer sources of sulfur.


 
Interaction between S and other nutrients in soil
 
The presence of anions like sulfate (SO4) in the soil solution relies on having equivalent amounts of counter cations such as calcium (Ca2+), magnesium (Mg2+), sodium (Na+) and potassium (K+). Consequently, the availability of sulfate is influenced by the concentration of these cations within the soil solution. During the oxidation of reduced sulfur species to sulfate, hydrogen ions are released, which can displace other cations from soil colloids through exchange processes. These cations may help maintain the balance of sulfate in the soil solution. However, cations such as calcium (Ca2+) can limit sulfate availability by forming insoluble compounds like calcium sulfate (CaSO4). When calcium carbonate (CaCO3) is added, it can result in higher levels of soluble sulfate. This effect may be attributed to the release of adsorbed sulfate due to an increase in soil pH (Anandham et al., 2011).
 
Sulfur oxidizing bacteria
 
Different microorganisms, including prokaryotes and green sulfur bacteria, have been identified that use sulfur compounds as electron donors, either obligately or facultatively and convert them to sulfate (Rana et al., 2020). Alpha-, Beta- and Gammaproteobacteria are the prokaryotes  that oxidize sulfur. In addition to chemolithotrophs and photolithotrophs, mixotrophs, photoheterotrophs and heterotrophs can be classified into these prokaryotes based on their physiological characteristics. A chemolithotroph, or chemosynthetic autotroph, includes members from bacteria and Archaea. All three categories include some important organisms in geomicrobiology (Zhao et al., 2022). These microorganisms obtain energy for their metabolic processes from the oxidation of inorganic substances and incorporate carbon as CO2, HCO3-, or CO (Kazemi et al., 2021). Bacteria are known to be photolithotrophs, but Archaea are not known to be photolithotrophs. The photosynthesis process converts sunlight into chemical energy, which is used by these microorganisms to perform   metabolic activities and encapsulates carbon as CO2, HCO3, or CO3 (Dahl 2020; Nosalova et al., 2023). There are some microorganisms that produce oxygen as a byproduct of photosynthesis, while there are others that cannot release oxygen during photosynthesis (Khasimov et al., 2021). Photoheterotrophs are primarily found among bacteria, although a few Archaea, like extreme halophiles, are also included. Heterotrophs include both bacteria and archaea, which get energy from sunlight but get carbon from organic carbon. The organisms oxidize organic compounds for energy and assimilate organic compounds for carbon. They can either respire (oxidizing their energy source) through anaerobic processes or ferment their energy source via disproportionate (Dahl, 2020). Mixotrophs consist of certain bacteria and Archaea. They can simultaneously derive energy from the oxidation of reduced carbon compounds and oxidizable inorganic compounds and may obtain carbon from both organic sources and CO2 at the same time, or they may completely derive energy from oxidizing an inorganic compound while sourcing their carbon from organic compounds (Table 3 and 4).

​

Table 3: Some of aerobic sulfur oxidizing bacteria (Zhang et al., 2025).



​

Table 4: Some anaerobic sulfur oxidizing bacteria (Zhang et al., 2025).



Sulfur-oxidizing bacteria may benefit from mixotrophic metabolism. Sulfur-oxidizing bacteria may benefit from co-oxidization of sulfur compounds along with organic substrates because low levels of sulfur compounds might inhibit growth (Nyamath et al., 2024). When grown in a mixotrophic medium containing glucose/glutamate/ acetate and thiosulfate, Starkeya novella and Thioclava pacifica oxidized thiosulfate and increased growth. Several studies have found that bacteria can develop in environments that contain glucose and organic materials that contain thiosulfate, in which case the organic material influences thiosulfate oxidation in Thiovirga in T. intermedius and Thiovirga sulfuroxydans (Yousuf et al., 2014). Conversely, thiosulfate has been found to hinder glucose uptake by impacting the enzymes involved in the glucose metabolic pathways, specifically the Entner-Doudoroff and pentose phosphate pathways in T. intermedius, Starkeya novella and Paracoccus versutus (formerly Thiobacillus A2) (Kumar et al., 2020; Anandham et al., 2011). Anandham et al., (2009a, b) discovered a mixotrophic metabolism utilizing thiosulfate/succinate or acetate in Methylobacterium oryzae, Methylobacterium fujisawaense, Methylobacterium goesingense and Burkholderia kururiensis subsp. thiooxydans. 
 
Isolation and characterization of sulfur oxidizing bacteria
 
In 1904, Beijerinck successfully isolated thiosulfate-oxidizing bacteria (Thiobacillus thioparus) from both freshwater canal sediment and saltwater environments. He also noted the formation of a dense pellicle made of sulfur that enveloped the bacterial cells produced by T. thioparus. This organism has been extracted from a variety of sources including soil, ditch water, sewage and seawater, with its ability to oxidize sulfur and sulfide being examined by numerous researchers. Bounaga et al., (2022) isolated a microorganism that could quickly oxidize sulfur into sulfuric acid. This organism was characterized as a small, colorless, non-filamentous type that primarily utilized elemental sulfur for energy, without accumulating sulfur inside or outside its cells. In certain instances, sulfur formed a layer on the surface of the liquid or adhered to the walls of the flasks, while in other cultures, delicate membranes devoid of sulfur surfaced at the top. Some cultures exhibited a combination of these phenomena.

Anandham et al., (2011) obtained sulfur-oxidizing bacteria from their natural environment by utilizing mineral media that contained either elemental sulfur or thiosulfate as an energy source. It is possible to selectively differentiate neutrophilic from acidophilic species with the use of pH-varying media. Employing an acid ferrous sulfate medium often promotes the selection of A. ferrooxidans, while an anaerobic thiosulfate medium (pH 7) enriched with nitrate is particularly effective in isolating T. denitrificans and Acidiphilium acidophilum (formerly known as Thiobacillus acidophilus), which was initially found as a commensal of A. ferrooxidans. Nosalova et al., (2023) developed an enhanced medium that used gel rite as a gel for the isolation and counting of acidophilic chemolithotrophic Thiobacillus strains. Robust and well-defined dark brown circular colonies appeared on this medium within 48 hours. A spring water sample contained strains that are like Sulfolobus and Thermus, as well as thiosulfate-oxidizing microorganisms (Dahl, 2020). PH levels of approximately 4-6, temperatures of 40oC and yeast extract concentrations of 60 mg per 100 ml were identified as optimal conditions for thiosulfate oxidation (Kumar et al., 2020). The extraction of A. thiooxidans from the Yugama Crater Lake in Japan and examined its impact on the sulfate budget. Thiosulfate-oxidizing, base-producing organisms like Pseudomonas stulzeri, Pseudoaltermonas and Halomonas deleya were obtained from the marine and hydrothermal vents of New England (He et al., 2022). Oligonucleotide probes were created to detect Thiobacillus and Acidiphilium in environmental samples (Anandham et al., 2011). Wen et al., (2012) successfully isolated Acidithiobacillus from sewage sludge by utilizing a modified Waksman medium.

Recent studies have demonstrated that sulfur-oxidizing bacteria can survive in extremely alkaline and saline conditions. An abundance of obligate autotrophs has been found in saline, alkaline lakes in Central Asia, Africa and North America, which exist in relatively significant numbers under these extreme conditions. In the presence of sodium carbonate/bicarbonate-buffering media, all strains demonstrated excellence at a pH around 10; however, at pH lower than 7.5 and sodium concentrations below 0.2 M, they are not able to grow. Phylogenetic and physiological differences among the isolates led to the identification of two new Gammaproteobacteria genera: Thioalkalimicrobium and Thioalkalivibrio. One of three species in Thioalkalispira is obligately microaerophilic, Thioalkalispira microaerophila. (Kong et al., 2022). Recently, Anandham et al.,  (2005; 2007; 2008a, b; 2009a, b; 2010) have reported the isolation of numerous obligate and facultative chemolithotrophic thiosulfate-oxidizing bacteria from rhizosphere soils, noting their widespread occurrence in the rhizospheres of crop plants in Korea.
 
Mass multiplication that oxidize sulfur
 
Ensuring cell survival and functionality in both rhizosphere and non-rhizosphere soils is crucial for the effectiveness of any inoculation approach. To improve the introduction of large microbial populations and enhance their preservation in soil, inoculum formulations utilizing carrier materials have been implemented. The inoculant serves as the vehicle for transporting bacteria from the production site to the living plant, while the carrier is viewed as the means of delivering live microorganisms from the production facility to the agricultural field; however, there is currently no universal carrier or formulation available for effectively releasing microorganisms into the soil. Anandham et al., (2005; 2007) developed a pellet formulation for sulfur-oxidizing bacteria.
 
Role of sulfur bacteria in sulfur nutrition
 
As a result, almost all sulfur present in soil environments (over 95% of total sulfur) cannot be directly absorbed by plants. Organic matter contains around 95% of the total sulfur content of the soil. Breakdown or decomposition of organic matter results in mineralization of organic sulfur into the SO42", which will be available to plants (Blum et al., 2013). Sulfate is produced more quickly by using sulfur-oxidizing bacteria. In recent years, sulfur-oxidizing bacteria have become increasingly popular as growth promoters that improve plant yields during critical growth phases. Groundnut nodules were increased by 32 per cent and nodule dry weight was increased by 43 percent, respectively, when Thiobacillus sp. was introduced 60 kg per hectare (Table 3) (Anandham et al., 2007). When sulfur and Acidithiobacillus were applied along with phosphate and potash rocks, sugarcane stalk dry matter yield was significantly enhanced (Stamford et al., 2015).
 
Factors influencing SOB in Farming system
 
Soil temperature
 
Temperature greatly influences sulfur mineralization in soil. A temperature below 10oC and a temperature exceeding 40oC significantly reduce the rate of sulfur mineralization, whereas around 30oC is the optimal temperature. In multiple studies, sulfur oxidation rates have been shown to increase as soil incubation temperatures rise. For example, sulfur oxidation rates after 57 days of incubation were 8% at 5oC, 22% at 15oC and 47% at 30oC (Watling et al., 2016).
 
Soil pH
 
pH plays a major role in the bio-oxidation of sulfur in the soil. If the soil pH is between 6.5 and 6.0, sulfur oxidation rate increases, but when the pH decreases, sulfur oxidation rate decreases. Neutral Thiobacillus species and heterotrophs, which thrive in neutral to alkaline soil conditions, are common sulfur-oxidizing bacteria (SOBs). In the upper 30 cm of the soil profile, pH and electrical conductivity (EC) are negatively related to the plant-available sulfur, while in the lower 30-60 cm, they are positively related to organic carbon. (Kang et al., 2021).
 
Soil moisture
 
Moisture and aeration, together with temperature and pH, are vital abiotic factors affecting sulfur oxidation in soils, showing a parabolic relationship where oxidation is minimal at low moisture, increases as moisture approaches an optimal level (around 60% of field capacity) and peaks before declining. Soil moisture is affected by factors like soil type, texture and aeration, with adequate aeration being vital for the growth of sulfur-oxidizing bacteria, as poor aeration can impair their development and reduce sulfur oxidation rates (Pourbabaee et al., 2020).
 
Land cultivation and agronomic practices
 
Conventional tillage can lead to a swift reduction in soil organic matter, resulting in decreased sulfur levels and diminished long-term fertility of the soil. Soils that are regularly treated with Sulfur show a higher count of Thiobacillus spp., which suggests a greater potential for Sulfur oxidation compared to soils that have never been treated with Sulfur, indicating a priming effect from the oxidation by Thiobacillus spp. This type of soil also influences the rate of sulfur oxidation. Typically, sulfur oxidation occurs at a higher rate in sandy loam, followed by clay soil, while it is significantly lower in silty clay soil (Malik et al., 2021).
 
Crop and cropping system
 
As demonstrated in fallow fields, the type of crop and cropping system plays a significant role in influencing sulfur transformations within the soil, primarily because of the heightened microbial biomass present in the rhizosphere. Implementing cropping techniques that minimize nutrient loss and enhance soil organic matter could be beneficial for increasing the availability of sulfur in the soil during years conducive to mineralization, all while reducing the dependency on added fertilizer sulfur (Iannucci et al., 2021).
 
Soil microbes
 
Soil microorganisms play a crucial role in transforming reduced sulfur compounds in the soil into a form that can be absorbed (SO42"). While many microorganisms participate in sulfur oxidation, bacteria, particularly Thiobacillus and related species, have a significant effect on this process (Rana et al., 2020). The quantity and activity of microbial biomass affect the rate at which elemental sulfur is oxidized in agricultural soils. The oxidation of sulfur in soil is primarily carried out by heterotrophic sulfur-oxidizing groups, with autotrophic microorganisms following behind. A large proportion of organic sulfur in the soil exists as sulfate esters (up to 60%), which can be readily mineralized through the action of enzymes produced by a wide range of heterotrophic bacteria, including Pseudomonas and Thiobacillus species (Rana et al., 2020). Certain microbial species or genera within a crop’s rhizosphere have a more significant influence on sulfur cycling than others found in the crop itself. However, due to the fact that most soil microorganisms cannot be cultivated in artificial media, this functional specialization has been largely overlooked. As a result of this limitation, cultivation-based methods offer a distorted view of microbial ecology in the soil. To gain a better understanding of the involvement of soil microorganisms in sulfur cycling, a targeted investigation into functional diversity is necessary. This can be achieved through cultivation-independent techniques like stable isotope probing and soil genetic profiling (Alcolombri et al., 2022; Dumont and Hernández García,  2019).
 
Particle size
 
Effective oxidation requires that A. thiooxidans come into direct contact with Sp  particles (Ranadev et al., 2023). To enhance the effectiveness of sulfur fertilizer (Sp ), the particle size of applied sulfur should ideally fall between 80 and 1000 mesh or be even finer.
 
Soil organic matter
 
Organic carbon and soil organic matter have a significant positive relationship with soil sulfur. Organic sulfur comprises a varied array of soil microorganisms and partially decomposed remains of plants, animals and microbes, which accounts for about 95% of the total sulfur found in most agricultural soils (Kodavali and Khurana, 2022). Fresh organic sulfur decomposes more quickly than older organic sulfur, which is released at a slower rate. Organic materials such as wheat straw, broom grass clippings, farmyard manure, poultry litter and peat moss have been found to enhance soil sulfur levels (Lee et al., 2021; Malik et al., 2021).
 
Prospects for the future in Agriculture
 
The use of SOB extends beyond agriculture and encompasses a variety of other sectors. In environmental science, they are vital in neutralizing H2S, remediating soil and treating wastewater. Furthermore, with the current focus on nanotechnology, SOB is employed in the creation of nanoscale sulfide particles that exhibit superior optical, electronic and mechanical attributes compared to other metal nanoparticles. Furthermore, SOB is crucial for increasing the operational lifespan of bio-electrochemical fuel cells, particularly sediment microbial fuel cells (SMFC), by reducing phosphorus discharge from the sediment, thereby supporting electrical current production. SOB thrives in extreme environmental settings, including high salinity regions (halophytes) and acidic soils (acidophilic), offering extensive genetic variation that can be utilized to tackle various challenges in agriculture and other scientific disciplines through biotechnological methods. Despite its potential, the low biomass of SOB, the acidification of the process solution and the selectivity of Bio-S0 hinder its industrial use. Consequently, additional efforts must be made to enhance the BDS process for industrial purposes through various research avenues. In the energy field, researchers are utilizing cellulose nanofiber derived from SOB to enhance lithium-sulfur batteries (LSBs). In the field of metallurgy, the bioleaching of different metals, including Cu, Zn and Fe, using SOB proves to be cost-effective. At present, CRISPR-Cas is a widely used method for genome editing. This system can be employed to create genetically modified SOB with improved thermostability, solvent resistance and broader substrate specificity, facilitating better utilization of SOB in agriculture and other sectors.

CONCLUSION

A growing number of soils around the globe are experiencing sulfur deficiency, which can result in lower crop productivity and yield declines. In India, about 46% of soils lack adequate sulfur, causing crop yields to drop by 20% to 40%. Similar observations have been reported from various regions worldwide. Although sulfur exists primarily in organic forms in most soils, it is not easily accessible for plants to absorb. Utilizing S0 presents a cost-effective option for swiftly restoring sulfur levels, but it requires oxidation to sulfate for plant uptake. The oxidation efficiency of S0 in soil is affected by various soil and environmental factors, along with the particle size of sulfur and the diversity of soil microorganisms. The biotechnological use of sulfur-oxidizing bacteria (SOB) provides a chance to create innovative biofertilizers and enhance the sulfur oxidation process in soil. While there has been evidence of the positive impacts of sulfur combined with SOB on crop growth and yields, research in this area is still limited and the persistence of SOB in different formulations has not been investigated. Additionally, SOB has several traits that promote plant growth, such as the production of IAA, siderophores, antimicrobial substances and ACC deaminase activity, which can be utilized as beneficial properties in biofertilizers. Additional research is required to explore and examine the different biochemical pathways involved in sulfur oxidation across various soils in diverse agroclimatic regions.

CONFLICT OF INTEREST

The authors declare no commercial or financial conflict of interest.

REFERENCES


  1. Alcolombri, U., Pioli, R., Stocker, R. and Berry, D. (2022). Single-cell stable isotope probing in microbial ecology. ISME communi- cations. 2(1): 55.

  2. Anandham, R., Gandhi, P.I., Madhaiyan, M. and Sa, T. (2008a). Potential plant growth promoting traits and bioacidulation of rock phosphate by thiosulfate oxidizing bacteria isolated from crop plants. Journal of Basic Microbiology. 48(6): 439-447.

  3. Anandham, R., Gandhi, P.I., SenthilKumar, M., Sridar, R., Nalayini, P. and Sa, T.M. (2011). Sulfur-oxidizing bacteria: A novel bioinoculant for sulfur nutrition and crop production. Bacteria in agrobiology: Plant Nutrient Management. pp. 81-107.

  4. Anandham, R., Indira Gandhi, P., Kwon, S. W., Sa, T.M. and Jee, H.J. (2009a). Taxonomic characterization of facultative chemolithoautotrophic strains ATSB16 isolated from rhizosphere soils. International workshop on microbial sulfur metabolism. March-15-18. Tomar, Portugal. pp. 151.

  5. Anandham, R., Indira Gandhi, P., Kwon, S.W., Sa, T.M., Kim, Y.K. and Jee, H.J. (2009b). Mixotrophic metabolism in Burkholderia kururiensis subsp. thiooxydans subsp. nov., a facultative chemolithoautotrophic thiosulfate oxidizing bacterium isolated from rhizosphere soil and proposal for classification of the type strain of Burkholderia kururiensis as Burkholderia kururiensis subsp. kururiensis subsp. nov. Archives of Microbiology. 191: 885-894.

  6. Anandham, R., Indiragandhi, P., Kwon, S.W., Sa, T.M., Jeon, C.O., Kim, Y.K. and Jee, H.J. (2010). Pandoraea thiooxydans sp. nov., a facultatively chemolithotrophic, thiosulfate-oxidizing bacterium isolated from rhizosphere soils of sesame (Sesamum indicum L.). International Journal of Systematic and Evolutionary Microbiology. 60(1): 21-26.

  7. Anandham, R., Indiragandhi, P., Madhaiyan, M., Ryu, K.Y., Jee, H.J. and Sa, T.M. (2008b). Chemolithoautotrophic oxidation of thiosulfate and phylogenetic distribution of sulfur oxidation gene (soxB) in rhizobacteria isolated from crop plants. Research in Microbiology. 159(9-10): 579-589.

  8. Anandham, R., Sridar, R., Nalayini, P., Madhaiyan, M., Gandhi, P.I., Choi, K.H. and Sa, T.M. (2005). Isolation of sulfur oxidizing bacteria from different ecological niches. Korean Journal of Soil Science and Fertilizer. 38(4): 180-187.

  9. Anandham, R., Sridar, R., Nalayini, P., Poonguzhali, S. and Madhaiyan, M.J.M.R. (2007). Potential for plant growth promotion in groundnut (Arachis hypogaea L.) cv. ALR-2 by co-inoculation of sulfur-oxidizing bacteria and Rhizobium. Microbiological Research. 162(2): 139-153.

  10. Assefa, S., Haile, W. and Tena, W. (2021). Effects of phosphorus and sulfur on yield and nutrient uptake of wheat (Triticum aestivum L.) on Vertisols, North Central, Ethiopia. Heliyon. 7(3).

  11. Balagangathar, K., Kalaiyarasan, C., Kandasamy, S., Madhavan, S. and Jawahar, S. (2024). Impact of nitrogen and sulphur application on the growth and yield of groundnut (Arachis hypogeae L.). Crop Research. 59(3,4): 138-142.

  12. Beijerinck, M. W. (1904). Phenomenes de reduction produits par les microbes. Archives Neerlandaises des Sciences Exactes et Naturelles. 2(13): 1-157.

  13. Blum, S. C., Lehmann, J., Solomon, D., Caires, E.F. and Alleoni, L.R.F. (2013). Sulfur forms in organic substrates affecting S mineralization in soil. Geoderma. 200: 156-164.

  14. Bounaga, A., Alsanea, A., Lyamlouli, K., Zhou, C., Zeroual, Y., Boulif, R. and Rittmann, B.E. (2022). Microbial transformations by sulfur bacteria can recover value from phosphogypsum: A global problem and a possible solution. Biotechnology Advances. 57: 107949.

  15. Bouranis, D.L., Malagoli, M., Avice, J.C. and Bloem, E. (2020). Advances in plant sulfur research. Plants. 9(2): 256.

  16. Camberato, J. and Casteel, S. (2017). Sulfur deficiency. Purdue Univ. Dep. of Agronomy, Soil Fertility Update.

  17. Chaudhary, S., Dhanker, R., Kumar, R. and Goyal, S. (2022). Importance of legumes and role of Sulphur oxidizing bacteria for their production: A review. Legume Research-An International Journal. 45(3): 275-284. doi: 10.18805/LR-4415.

  18. Dahl, C. (2020). A biochemical view on the biological sulfur cycle. Environmental technologies to treat sulfur pollution: Principles and Engineering. 2: 55-96.

  19. Das, S., Khanam, R., Bag, A.G., Chatterjee, N., Hazra, G.C., Kundu, D. and Ghouse, S.K.P. (2022). Spatial distribution of sulphur and its relationship with soil attributes under diverse agro- climatic zones of West Bengal, India. Journal of the Indian Society of Soil Science. 69(4): 401-410.

  20. Dumont, M. G. and Hernández, M. (2019). Stable isotope probing. Methods and Protocols Totowa, NJ, US: Humana Press.

  21. Fujita, Y. and Uesaka, K. (2022). Nitrogen fixation in cyanobacteria. Cyanobacterial Physiology. pp. 29-45.

  22. Germida, J.J., Wainwright, M. and Gupta, V.V. (2021). Biochemistry of sulfur cycling in soil. In Soil biochemistry. CRC Press. pp. 1-53.

  23. Harborne, A.R., Rogers, A., Bozec, Y.M. and Mumby, P.J. (2017). Multiple stressors and the functioning of coral reefs. Annual Review of Marine Science. 9(1): 445-468.

  24. He, Y., Zeng, X., Xu, F. and Shao, Z. (2022). Diversity of mixotrophic neutrophilic thiosulfate-and iron-oxidizing bacteria from deep-sea hydrothermal vents. Microorganisms. 11(1): 100.

  25. Iannucci, A., Canfora, L., Nigro, F., De Vita, P. and Beleggia, R. (2021). Relationships between root morphology, root exudate compounds and rhizosphere microbial community in durum wheat. Applied Soil Ecology. 158: 103781.

  26. Kang, E., Li, Y., Zhang, X., Yan, Z., Wu, H., Li, M. and Kang, X. (2021). Soil pH and nutrients shape the vertical distribution of microbial communities in an alpine wetland. Science of the Total Environment. 774: 145780.

  27. Kazemi, E., Soofiyani, S.R., Ahangari, H., Eyvazi, S., Hejazi, M.S. and Tarhriz, V. (2021). Chemolithotroph Bacteria: From biology to application in medical sciences. Crescent Journal of Medical and Biological Sciences. 8(2).

  28. Khan, B.A., Hussain, A., Elahi, A., Adnan, M., Amin, M.M., Toor, M.D. and Ahmad, R. (2020). Effect of phosphorus on growth, yield and quality of soybean (Glycine max L.): A review. International Journal of Advanced Research. 6(7): 540-545.

  29. Khasimov, M.K., Laurinavichene, T.V., Petushkova, E.P. and Tsygankov, A.A. (2021). Relations between hydrogen and sulfur metabolism in purple sulfur bacteria. Microbiology. 90: 543-557.

  30. Kodavali, M.R. and Khurana, M.P.S. (2022). Sulphur and its significance in higher pulse production. Environment Conservation Journal. 23(3): 367-373.

  31. Kong, Y.H., Ren, W.T., Xu, L., Cheng, H., Zhou, P., Wang, C.S. and Xu, X.W. (2022). Mesobacterium pallidum gen. nov., sp. nov., Heliomarina baculiformis gen. nov., sp. nov. and Oricolaindica sp. nov., three novel Alphaproteobacteria members isolated from deep-sea water in the southwest Indian ridge. International Journal of Systematic and Evolutionary Microbiology. 72(2): 005236.

  32. Kulczycki, G. (2021). The effect of elemental sulfur fertilization on plant yields and soil properties. Advances in Agronomy. 167: 105-181.

  33. Kumar, M., Zeyad, M.T., Choudhary, P., Paul, S., Chakdar, H. and Rajawat, M.V.S. (2020). Thiobacillus. In Beneficial microbes in agro-ecology. Academic Press. pp. 545-557.

  34. Lee, S.Y., Kim, E.G., Park, J.R., Ryu, Y.H., Moon, W., Park, G.H. and Kim, K.M. (2021). Effect on chemical and physical properties of soil each peat moss, elemental sulfur and sulfur-oxidizing bacteria. Plants. 10(9): 1901.

  35. Malik, K.M., Khan, K.S., Billah, M., Akhtar, M.S., Rukh, S., Alam, S. and Khan, N. (2021). Organic amendments and elemental sulfur stimulate microbial biomass and sulfur oxidation in alkaline subtropical soils. Agronomy. 11(12): 2514.

  36. Narayan, O.P., Kumar, P., Yadav, B., Dua, M. and Johri, A.K. (2023). Sulfur nutrition and its role in plant growth and development. Plant Signaling and Behavior. 18(1): 2030082.

  37. Noman, H.M., Rana, D.S., Choudhary, A.K., Dass, A., Rajanna, G.A. and Pande, P. (2020). Improving productivity, quality and biofortification in groundnut (Arachis hypogaea L.) through sulfur and zinc nutrition in alluvial soils of the semi-arid region of India. Journal of Plant Nutrition. 44(8): 1151-1174.

  38. Nosalova, L., Piknova, M., Kolesarova, M. and Pristas, P. (2023). Cold sulfur springs-neglected niche for autotrophic sulfur- oxidizing bacteria. Microorganisms. 11(6): 1436.

  39. Nyamath, S., Subburamu, K., Kalyanasundaram, G.T., Balachandar, D., Suresh, M. and Anandham, R. (2024). Multifarious characteristics of sulfur-oxidizing bacteria residing in rice rhizosphere. Folia Microbiologica. 69(2): 395-405.

  40. Park, S., Kim, H.W., Joo Lee, C., Kim, Y. and Sung, J. (2024). Profiles of volatile sulfur compounds in various vegetables consumed in Korea using HS-SPME-GC/MS technique. Frontiers in Nutrition. 11: 1409008.

  41. Pourbabaee, A.A., Koohbori Dinekaboodi, S., Seyed Hosseini, H.M., Alikhani, H.A. and Emami, S. (2020). Potential application of selected sulfur-oxidizing bacteria and different sources of sulfur in plant growth promotion under different moisture conditions. Communications in Soil Science and Plant Analysis. 51(6): 735-745.

  42. Ramamoorthy, P. and Ariraman, R. (2023). Effect of phosphorus and sulphur application on growth, yield attributes, nutrient uptake, quality and economics of blackgram (Vigna mungo L.): A review. Agricultural Reviews. 44(2): 252-258. doi: 10.18805/ag.R-2180.

  43. Rameez, M.J., Pyne, P., Mandal, S., Chatterjee, S., Alam, M., Bhattacharya, S. and Ghosh, W. (2021). Two pathways for thiosulfate oxidation in the alphaproteobacterial chemolithotroph Paracoccus thiocyanatus SST. Microbiological Research. 230: 126345.

  44. Rana, K., Rana, N. and Singh, B. (2020). Applications of sulfur oxidizing bacteria. In Physiological and biotechnological aspects of extremophiles. Academic Press. pp. 131-136.

  45. Ranadev, P., Revanna, A., Bagyaraj, D.J. and Shinde, A.H. (2023). Sulfur oxidizing bacteria in agro ecosystem and its role in plant productivity-a review. Journal of Applied Micro- biology. 134(8): 161.

  46. Shah, S.H., Islam, S. and Mohammad, F. (2022). Sulphur as a dynamic mineral element for plants: A review. Journal of Soil Science and Plant Nutrition. 22(2): 2118-2143.

  47. Sharma, A.K., Samuchia, D., Sharma, P.K., Mandeewal, R.L., Nitharwal, P.K. and Meena, M. (2022). Effect of nitrogen and sulphur in the production of the mustard crop [Brassica juncea (L.)]. International Journal of Environment and Climate Change. 12: 132-137.

  48. Sharma, J., Dua, V.K., Sharma, S., Choudhary, A.K., Kumar, P. and Sharma, A. (2022). Role of plant nutrition in disease development and management. In Sustainable Management  of Potato Pests and Diseases. Singapore: Springer Singapore. pp. 83-110.

  49. Singh, N., Kushwaha, H.S. and Singh, A. (2020). Integrated nutrient management on growth, yield, nutrient uptake and fertility balance in soybean (Glycine max L.)-wheat (Triticum aestivum L.) cropping sequence. International Journal of Bio-resource and Stress Management. 11(4): 405-413.

  50. Singh, R.P., Singh, S.K., Yadav, P.K. and Singh, S.N. (2010). Effect of sulphur and calcium on yield and quality of mustard (Brassica juncea).

  51. Skwierawska, M., Benedycka, Z., Jankowski, K. and Skwierawski, A. (2016). Sulphur as a fertiliser component determining crop yield and quality. Journal of Elementology. 21(2): 609-623. doi: 10.5601/jelem.2015.20.3.992.

  52. Slocum, R.D. and Flores, H.E. (2024). Biochemistry and physiology of polyamines in plants. CRC press.

  53. Stamford, N.P., Figueiredo, M. V., da Silva Junior, S., Freitas, A.D.S., Santos, C.E.R. and Junior, M.A.L. (2015). Effect of gypsum and sulfur with Acidithiobacillus on soil salinity alleviation and on cowpea biomass and nutrient status as affected by PK rock biofertilizer. Scientia Horticulturae. 192: 287-292.

  54. Stamford, N.P., Silva Junior, S.D., Rosália, C.E.D., Santos, S., Freitas, A.D.S.D., Lira Júnior, M. D. A. and Barros, M.D.F.C. (2013). Cowpea nodulation, biomass yield and nutrient uptake, as affected by biofertilizers and rhizobia, in a sodic soil amended with Acidithiobacillus. ActaScientiarum. Agronomy. 35: 453-459.

  55. Stellhorn, J.R., Hayakawa, S., Klee, B.D., Paulus, B., Link Vasco, J., Rinn, N. and Pilgrim, W. C. (2022). Local structure of amorphous organotin sulfide clusters by low energy X ray absorption fine structure. Physica Status Solidi (b). 259(9): 2200088.

  56. Tabak, M., Lisowska, A., Filipek-Mazur, B. and Antonkiewicz, J. (2020). The effect of amending soil with waste elemental sulfur on the availability of selected macro elements and heavy metals. Processes. 8(10): 1245.

  57. Valle, S.F., Giroto, A.S., Klaic, R., Guimaraes, G.G. and Ribeiro, C. (2019). Sulfur fertilizer based on inverse vulcanization process with soybean oil. Polymer Degradation and Stability. 162: 102-105.

  58. Velu, G., Palanichamy, V. and Rajan, A.P. (2018). Phytochemical and pharmacological importance of plant secondary metabolites in modern medicine. Bioorganic Phase in Natural food: An Overview. pp. 135-156.

  59. Watling, H.R., Johnson, J.J., Shiers, D.W., Gibson, J.A.E., Nichols, P.D., Franzmann, P.D. and Plumb, J.J. (2016). Effect of temperature and inoculation strategy on Cu recovery and microbial activity in column bioleaching. Hydrometallurgy. 164: 189-201.

  60. Wen, Y.M., Wang, Q.P., Tang, C. and Chen, Z.L. (2012). Bioleaching of heavy metals from sewage sludge by Acidithiobacillus thiooxidans-a comparative study. Journal of Soils and Sediments. 12: 900-908.

  61. Yousuf, B., Kumar, R., Mishra, A. and Jha, B. (2014). Unravelling the carbon and sulphur metabolism in coastal soil ecosystems using comparative cultivation-independent genome-level characterization of microbial communities. PLoS One. 9(9): e107025.

  62. Zenda, T., Liu, S. Dong, A. and Duan, H. (2021). Revisiting Sulphur - The once neglected nutrient: It’s roles in plant growth, metabolism, stress tolerance and crop production. Agriculture. 11(7): 626.

  63. Zhang, Y., Wang, Q., Rogers, M. J. and He, J. (2025). Autotrophic denitrification under anoxic conditions by newly discovered mixotrophic sulfide-oxidizing bacterium. Bioresource Technology. pp. 132553.

  64. Zhao, C., Wang, J., Zang, F., Tang, W., Dong, G. and Nan, Z. (2022). Water content and communities of sulfur-oxidizing bacteria affect elemental sulfur oxidation in silty and sandy loam soils. European Journal of Soil Biology. 111: 103419.
Published In
Agricultural Reviews
Article Metrics
Metrics Icon
0
Views
0
Citations
Reviewed By
Share Article
Download Article
In this Article
    Contact us
    Follow us

    Review Article

    Sulfur Nutrition in Plant Growth Promotion by Sulfur Oxidizing Bacteria: A Review

    K
    K. Sowmya1,*
    S
    S.L. Sivapriya2
    1Department of Agricultural Microbiology, School of Agricultural Sciences, Bharath Institute of Higher Education and Research, Tambaram, Chennai-600 001, Tamil Nadu, India.
    2Department of Science, Janani Public School, Bangalore-560 001, Karnataka, India.

    ABSTRACT

    Since sulfur is a vital nutrient for plant development, a lack of sulfur can result in significant reductions in crop yield. Sulfur deficiency often results in the addition of sulfur fertilizers to soil, typically in reduced forms like elemental sulfur. However, the reduced sulfur fertilizers must be converted to sulfate by microbes before they can be utilized by plants. The purpose of this review article is to explore the natural occurrence of sulfur in soil, the overall conversions that sulfur undergoes, its function in plant physiology, the variety and microbial oxidation of different reduced sulfur forms, it can boost plant growth by measuring sulfur oxidation in soil and modifying factors that influence sulfur oxidation. 

    INTRODUCTION

    Besides nitrogen, phosphorus and potassium, sulfur (S) is becoming recognized as an   essential nutrient for plants. All compounds containing reduced sulfur are composed of cysteine and methionine, which form the building blocks of cysteine and methionine (Sharma et al., 2022). Sulfur is crucial for the survival of both plants and animals. The first documented case of sulfur deficiency was reported in 1933, despite being essential to plants in quantities like phosphorus. The initial observation of sulfur deficiency in wetland rice occurred in 1938. Both dryland crops and wetland rice have been identified as being negatively affected by sulfur deficiency over the past decade. Tropical regions are notorious for sulfur deficiencies arising in different types of andosols, vertisols, alfisols, ultisols and oxysols. Sulfur deficiency has been documented in wetland rice from Bangladesh, Burma, India, Indonesia, Japan, the Philippines and Sri Lanka. Reports indicate that 23 different crops in 40 tropical nations have shown positive responses to sulfur. Low sulfur fertilizer applications have increased, organic manure use has fallen, intensive cropping practices have declined and atmospheric pollution has decreased (Camberato and Casteel, 2017). Sulfur fertilizers, typically in reduced form like elemental sulfur, are used to resolve sulfur deficiencies in soils. The application of sulfur oxidizers accelerates the natural oxidation process of sulfur and hastens the production of sulfates, thus making them accessible to plants during crucial growth phases, which ultimately leads to higher crop yields (Valle et al., 2019; Skwierawska et al., 2016; Anandham et al., 2007; 2008a; Stamford et al., 2013; Stamford et al., 2015). A variety of microorganisms, including prokaryotes and green sulfur bacteria, have been identified that either obligately or facultatively use sulfur compounds as electron donors and oxidize these compounds into sulfate. Sulfur oxidizing bacteria such as Thiooxidans, Pseudaminobacter salicylatoxidans and Paracoccus are recommended as inoculants for different rice-growing ecosystems. Therefore, this study has isolated microorganisms from several ecological environments, but currently, there is no appropriate sulfur bio-inoculant available (Rameez et al., 2021). This review article discusses the natural occurrence of sulfur in soil, the general transformations of S, the physiological role of sulfur in plants, the diversity and microbiological oxidation of various forms of reduced S, methodologies for quantifying sulfur oxidation in soil, factors that influence S oxidation in soil and the implications of using sulfur-oxidizing bacteria (SOB) as plant growth promoters in the agro-ecosystem.
     
    Sulfur in soil 
     
    Among the 105 elements that compose the Earth’s crust, sulfur is found in a concentration of approximately 0.03%, ranking as the 17th most prevalent element. The elemental sulfur found in soil is primarily the mineral sulfides, sulfates, hydrogen sulfides and organic sulfur compounds. Minerals such as pyrite (FeS2) provide most of the sulfur in soils. Soil redox potential is closely linked to the oxidation state of sulfur in pyrite during weathering and soil formation. Reactions involving the oxidation and reduction of sulfur occur quite readily, leading to a wide variety of reactions that sulfur experiences in the soil. Soil sulfur content is generally   influenced by three factors: (1) organic matter, (2) clay percentages and clay minerals, (3) levels of iron and aluminum oxides.

    The organic sulfur content in soil rises with increased humus levels. Peat and marsh soils have a high concentration of organic sulfur. In the South Pacific, the total sulfur content tends to be lower in soils with minimal organic matter (Germida et al., 2021). Organic matter and sulfur deficiency are common in tropical soils due to weathering and leaching. In southern China, there is a positive correlation between total sulfur and the percentage of clay. Soils with iron and aluminum oxides retain sulfur longer than those with coarse textures, partly because they contain more organic matter (Das et al., 2022).
     
    Fractions of soil sulfur
     
    Plant availability of sulfur(S) is not directly related to soil sulfur(S) levels. In soil, sulfur exists in several forms, so its availability to plants depends on how it is transformed and how it interacts with other sulfur fractions (Fig 1). (Germida et al., 2021).

    Fig 1: General distribution of various sulfur fractions present in soils (Germida et al., 2021).


     
    Organic sulfur compounds
     
    Like organic matter, organic sulfur(S) has a decreasing distribution in soil profiles as depth increases. There are three kinds of soil organic S: cation -bonded sulfide, non - cation- bonded sulfide and humus sulfide. Generally, humid and semiarid soils have large amounts of C-bonded organic S. Isolating this fraction is challenging due to the significant transformations that S-containing compounds undergo. In soil, trace amounts of sulfur can be found despite the fact that sulfur is only found in small amounts in amino acids (Kodavali and Khurana, 2022).

    Sulfate polysaccharides, like non-carbon-bonded sulfur, are thought to be present in many forms, including unidentified ester sulfates. A small portion of organic sulfur is found within soil biomass. However, the sulfur content in microbial tissue is highly reactive and plays a key role in the turnover of sulfur, impacting its availability to plants (Stellhorn et al., 2022; Ranadev et al., 2023).
     
    Inorganic S
     
    In soil, inorganic sulfur predominantly exists as sulfate. When oxygen is lacking, sulfur appears as its reduced form. Plants obtain sulfur through the soil’s liquid phase. A significant portion of sulfur in calcareous and saline soils is found as gypsum (CaSO4·2H2O). The solid phase of sulfur consists of sulfate retained in an adsorbed state in arid areas, such as CaSO4, MgSO4 and Na2SO4. Iron oxide and aluminum oxide can adhere to sulfate. This sorption primarily occurs through ion exchange facilitated by the charges present on clay minerals and oxides, with the process becoming more pronounced as soil pH decreases (Table 1) (Narayan et al., 2023).

    Table 1: Inorganic forms of sulfur in soil (Bouranis 2020).


     
    Plant sulfur and Its physiological role
     
    Sulfur compounds have a wide range of physiological functions. Two perspectives can be taken when looking at sulfur’s function: Directly within compounds and indirectly at the level of influencing nutrient synthesis. APS (adenosine - 5' phosphosulfate) and PAPS (3' – phosphoad-enosine - 5' phosphosulfate) are two of the primary sources of sulfur for crop plants. Sulfate serves as the main source of sulfur for crop plants (Fujita and Uesaka, 2022). This strongly implies that sulfur plays a role in the synthesis of chlorophyll. Ferredoxin is categorized as an iron-sulfur enzyme, which lacks a cofactor but typically has equal amounts of iron and sulfur atoms in a specific unstable form that can break down in the presence of acid. In the reduction of nitrogen, NADPH passes on reducing equivalents to ferredoxin, an iron-sulfur protein. Further studies have demonstrated sulfur’s role in the TCA cycle and glycolysis (Tabak et al., 2020).

    Sulfur has also been recognized as an essential factor in the synthesis of flavonoids and carotenoids. Additionally, sulfur is crucial for the synthesis of polyamines. The biochemical roles of naturally occurring polyamines include regulating the physical and chemical characteristics of membranes, influencing the structure and function of nucleic acids, modulating enzyme activities and overseeing molecular synthesis (Slocum and Flores, 2024).

    Isothiocyanates possess antibacterial and antifungal characteristics as well. Brassica species can prevent the infection of the mildew pathogen Peronospora parasitica through the enzyme-mediated production of allyliso thiocyanate from sinigrin following tissue injury (Velu et al., 2018). In pea plants, a reduced level of sulfur nutrition led to decreased levels of nitrogen, silicon, iron, calcium, magnesium, sulfur and crude ash content, while phosphorus and aluminum contents in both shoot and root tissues increased (Shah et al., 2022). When sulfur and zinc are applied, the presence of one nutrient tends to lower the concentration of the other in the shoots. The interaction between sulfur and zinc likely occurs at absorption sites as well as within the plants themselves (Noman et al., 2020).

    Allylisothiocyanate is the sharp and pungent compound found in mustard, which people consume in small quantities as a condiment. This isothiocyanate also serves as the primary flavor component in cabbage and other cruciferous vegetables (Harborne, 2014). Typically, local varieties of horseradish, both wild and cultivated, tend to be more pungent than imported types. Increasing sulfur levels led to a rise in allylisothiocyanate during decay, thereby enhancing its pungency. The allylsulfide content of Korean soil was positively correlated with sulfur availability (r=0.723, n=15, p=0.01) (Park et al., 2024).
     
    Sulfur effects on crops
     
    The growth of legume plants is adversely affected when soil levels of phosphorus and sulfur fall below critical threshold levels (Chaudhary et al., 2022). Compared to controls, elemental sulfur increased groundnut oil content by 5%, nodule biomass, pod yield, shoot length and dry matter while reducing chlorosis (Noman et al., 2020; Balagangathar et al., 2024). Sulfur increased the rate at which carbohydrates were converted into oil, resulting in more oil and yield per molecule (Singh et al., 2010). The oil content of sesame increased by 3.2% with a sulfur application of 50 kg per hectare (Assefa et al., 2021). Adding sulfur to mustard increased its oil content and seed yield (Sharma et al., 2022). Soybean leaf area, dry biomass, pod count and 100 seed weight were improved with an application of 30 kg sulfur per hectare (Khan et al., 2020). Wheat yield increases by 2.19 quintals per hectare due to an increase of 30 kg S per hectare, as well as an improvement of nitrogen, phosphorus and potassium absorption (Singh et al., 2020). Blackgram yield-related traits and overall yield were significantly enhanced by 30 kg of sulfur per hectare (Ramamoorthy and Ariraman, 2023). A micronized sulfur application increased wheat yield by 36% and sulfur uptake by 164%, according to Kulczycki, (2021). Rice, maize, field beans, wheat, cotton, sorghum and sunflower all grew better after sulfur application, according to Zenda et al., (2021).
     
    Deficiency symptoms
     
    Sulfur, which is a part of nitrate reductase, plays a crucial role in transforming nitrate into organic nitrogen. Therefore, a deficiency in sulfur disrupts nitrogen metabolism, accounting for the similarities in symptoms between sulfur and nitrogen deficiencies in various crops. Nevertheless, the symptoms are typically mild and not restricted to the older leaves. The appearance of sulfur deficiency is characterized by a light green hue affecting the entire plant. Legumes, particularly alfalfa, have a significant demand for sulfur, making them the first to exhibit signs of deficiency. In corn, sulfur deficiency can sometimes mimic other nutrient shortages like manganese or magnesium, leading to interveinal chlorosis; the upper leaves are often stripped, with veins appearing darker green than the surrounding tissues. To correct sulfur deficiency in crops, the application of sulfur-containing fertilizers is generally recommended (Table 2) (Bouranis, 2020).

    ​

    Table 2: Fertilizer sources of sulfur.


     
    Interaction between S and other nutrients in soil
     
    The presence of anions like sulfate (SO4) in the soil solution relies on having equivalent amounts of counter cations such as calcium (Ca2+), magnesium (Mg2+), sodium (Na+) and potassium (K+). Consequently, the availability of sulfate is influenced by the concentration of these cations within the soil solution. During the oxidation of reduced sulfur species to sulfate, hydrogen ions are released, which can displace other cations from soil colloids through exchange processes. These cations may help maintain the balance of sulfate in the soil solution. However, cations such as calcium (Ca2+) can limit sulfate availability by forming insoluble compounds like calcium sulfate (CaSO4). When calcium carbonate (CaCO3) is added, it can result in higher levels of soluble sulfate. This effect may be attributed to the release of adsorbed sulfate due to an increase in soil pH (Anandham et al., 2011).
     
    Sulfur oxidizing bacteria
     
    Different microorganisms, including prokaryotes and green sulfur bacteria, have been identified that use sulfur compounds as electron donors, either obligately or facultatively and convert them to sulfate (Rana et al., 2020). Alpha-, Beta- and Gammaproteobacteria are the prokaryotes  that oxidize sulfur. In addition to chemolithotrophs and photolithotrophs, mixotrophs, photoheterotrophs and heterotrophs can be classified into these prokaryotes based on their physiological characteristics. A chemolithotroph, or chemosynthetic autotroph, includes members from bacteria and Archaea. All three categories include some important organisms in geomicrobiology (Zhao et al., 2022). These microorganisms obtain energy for their metabolic processes from the oxidation of inorganic substances and incorporate carbon as CO2, HCO3-, or CO (Kazemi et al., 2021). Bacteria are known to be photolithotrophs, but Archaea are not known to be photolithotrophs. The photosynthesis process converts sunlight into chemical energy, which is used by these microorganisms to perform   metabolic activities and encapsulates carbon as CO2, HCO3, or CO3 (Dahl 2020; Nosalova et al., 2023). There are some microorganisms that produce oxygen as a byproduct of photosynthesis, while there are others that cannot release oxygen during photosynthesis (Khasimov et al., 2021). Photoheterotrophs are primarily found among bacteria, although a few Archaea, like extreme halophiles, are also included. Heterotrophs include both bacteria and archaea, which get energy from sunlight but get carbon from organic carbon. The organisms oxidize organic compounds for energy and assimilate organic compounds for carbon. They can either respire (oxidizing their energy source) through anaerobic processes or ferment their energy source via disproportionate (Dahl, 2020). Mixotrophs consist of certain bacteria and Archaea. They can simultaneously derive energy from the oxidation of reduced carbon compounds and oxidizable inorganic compounds and may obtain carbon from both organic sources and CO2 at the same time, or they may completely derive energy from oxidizing an inorganic compound while sourcing their carbon from organic compounds (Table 3 and 4).

    ​

    Table 3: Some of aerobic sulfur oxidizing bacteria (Zhang et al., 2025).



    ​

    Table 4: Some anaerobic sulfur oxidizing bacteria (Zhang et al., 2025).



    Sulfur-oxidizing bacteria may benefit from mixotrophic metabolism. Sulfur-oxidizing bacteria may benefit from co-oxidization of sulfur compounds along with organic substrates because low levels of sulfur compounds might inhibit growth (Nyamath et al., 2024). When grown in a mixotrophic medium containing glucose/glutamate/ acetate and thiosulfate, Starkeya novella and Thioclava pacifica oxidized thiosulfate and increased growth. Several studies have found that bacteria can develop in environments that contain glucose and organic materials that contain thiosulfate, in which case the organic material influences thiosulfate oxidation in Thiovirga in T. intermedius and Thiovirga sulfuroxydans (Yousuf et al., 2014). Conversely, thiosulfate has been found to hinder glucose uptake by impacting the enzymes involved in the glucose metabolic pathways, specifically the Entner-Doudoroff and pentose phosphate pathways in T. intermedius, Starkeya novella and Paracoccus versutus (formerly Thiobacillus A2) (Kumar et al., 2020; Anandham et al., 2011). Anandham et al., (2009a, b) discovered a mixotrophic metabolism utilizing thiosulfate/succinate or acetate in Methylobacterium oryzae, Methylobacterium fujisawaense, Methylobacterium goesingense and Burkholderia kururiensis subsp. thiooxydans. 
     
    Isolation and characterization of sulfur oxidizing bacteria
     
    In 1904, Beijerinck successfully isolated thiosulfate-oxidizing bacteria (Thiobacillus thioparus) from both freshwater canal sediment and saltwater environments. He also noted the formation of a dense pellicle made of sulfur that enveloped the bacterial cells produced by T. thioparus. This organism has been extracted from a variety of sources including soil, ditch water, sewage and seawater, with its ability to oxidize sulfur and sulfide being examined by numerous researchers. Bounaga et al., (2022) isolated a microorganism that could quickly oxidize sulfur into sulfuric acid. This organism was characterized as a small, colorless, non-filamentous type that primarily utilized elemental sulfur for energy, without accumulating sulfur inside or outside its cells. In certain instances, sulfur formed a layer on the surface of the liquid or adhered to the walls of the flasks, while in other cultures, delicate membranes devoid of sulfur surfaced at the top. Some cultures exhibited a combination of these phenomena.

    Anandham et al., (2011) obtained sulfur-oxidizing bacteria from their natural environment by utilizing mineral media that contained either elemental sulfur or thiosulfate as an energy source. It is possible to selectively differentiate neutrophilic from acidophilic species with the use of pH-varying media. Employing an acid ferrous sulfate medium often promotes the selection of A. ferrooxidans, while an anaerobic thiosulfate medium (pH 7) enriched with nitrate is particularly effective in isolating T. denitrificans and Acidiphilium acidophilum (formerly known as Thiobacillus acidophilus), which was initially found as a commensal of A. ferrooxidans. Nosalova et al., (2023) developed an enhanced medium that used gel rite as a gel for the isolation and counting of acidophilic chemolithotrophic Thiobacillus strains. Robust and well-defined dark brown circular colonies appeared on this medium within 48 hours. A spring water sample contained strains that are like Sulfolobus and Thermus, as well as thiosulfate-oxidizing microorganisms (Dahl, 2020). PH levels of approximately 4-6, temperatures of 40oC and yeast extract concentrations of 60 mg per 100 ml were identified as optimal conditions for thiosulfate oxidation (Kumar et al., 2020). The extraction of A. thiooxidans from the Yugama Crater Lake in Japan and examined its impact on the sulfate budget. Thiosulfate-oxidizing, base-producing organisms like Pseudomonas stulzeri, Pseudoaltermonas and Halomonas deleya were obtained from the marine and hydrothermal vents of New England (He et al., 2022). Oligonucleotide probes were created to detect Thiobacillus and Acidiphilium in environmental samples (Anandham et al., 2011). Wen et al., (2012) successfully isolated Acidithiobacillus from sewage sludge by utilizing a modified Waksman medium.

    Recent studies have demonstrated that sulfur-oxidizing bacteria can survive in extremely alkaline and saline conditions. An abundance of obligate autotrophs has been found in saline, alkaline lakes in Central Asia, Africa and North America, which exist in relatively significant numbers under these extreme conditions. In the presence of sodium carbonate/bicarbonate-buffering media, all strains demonstrated excellence at a pH around 10; however, at pH lower than 7.5 and sodium concentrations below 0.2 M, they are not able to grow. Phylogenetic and physiological differences among the isolates led to the identification of two new Gammaproteobacteria genera: Thioalkalimicrobium and Thioalkalivibrio. One of three species in Thioalkalispira is obligately microaerophilic, Thioalkalispira microaerophila. (Kong et al., 2022). Recently, Anandham et al.,  (2005; 2007; 2008a, b; 2009a, b; 2010) have reported the isolation of numerous obligate and facultative chemolithotrophic thiosulfate-oxidizing bacteria from rhizosphere soils, noting their widespread occurrence in the rhizospheres of crop plants in Korea.
     
    Mass multiplication that oxidize sulfur
     
    Ensuring cell survival and functionality in both rhizosphere and non-rhizosphere soils is crucial for the effectiveness of any inoculation approach. To improve the introduction of large microbial populations and enhance their preservation in soil, inoculum formulations utilizing carrier materials have been implemented. The inoculant serves as the vehicle for transporting bacteria from the production site to the living plant, while the carrier is viewed as the means of delivering live microorganisms from the production facility to the agricultural field; however, there is currently no universal carrier or formulation available for effectively releasing microorganisms into the soil. Anandham et al., (2005; 2007) developed a pellet formulation for sulfur-oxidizing bacteria.
     
    Role of sulfur bacteria in sulfur nutrition
     
    As a result, almost all sulfur present in soil environments (over 95% of total sulfur) cannot be directly absorbed by plants. Organic matter contains around 95% of the total sulfur content of the soil. Breakdown or decomposition of organic matter results in mineralization of organic sulfur into the SO42", which will be available to plants (Blum et al., 2013). Sulfate is produced more quickly by using sulfur-oxidizing bacteria. In recent years, sulfur-oxidizing bacteria have become increasingly popular as growth promoters that improve plant yields during critical growth phases. Groundnut nodules were increased by 32 per cent and nodule dry weight was increased by 43 percent, respectively, when Thiobacillus sp. was introduced 60 kg per hectare (Table 3) (Anandham et al., 2007). When sulfur and Acidithiobacillus were applied along with phosphate and potash rocks, sugarcane stalk dry matter yield was significantly enhanced (Stamford et al., 2015).
     
    Factors influencing SOB in Farming system
     
    Soil temperature
     
    Temperature greatly influences sulfur mineralization in soil. A temperature below 10oC and a temperature exceeding 40oC significantly reduce the rate of sulfur mineralization, whereas around 30oC is the optimal temperature. In multiple studies, sulfur oxidation rates have been shown to increase as soil incubation temperatures rise. For example, sulfur oxidation rates after 57 days of incubation were 8% at 5oC, 22% at 15oC and 47% at 30oC (Watling et al., 2016).
     
    Soil pH
     
    pH plays a major role in the bio-oxidation of sulfur in the soil. If the soil pH is between 6.5 and 6.0, sulfur oxidation rate increases, but when the pH decreases, sulfur oxidation rate decreases. Neutral Thiobacillus species and heterotrophs, which thrive in neutral to alkaline soil conditions, are common sulfur-oxidizing bacteria (SOBs). In the upper 30 cm of the soil profile, pH and electrical conductivity (EC) are negatively related to the plant-available sulfur, while in the lower 30-60 cm, they are positively related to organic carbon. (Kang et al., 2021).
     
    Soil moisture
     
    Moisture and aeration, together with temperature and pH, are vital abiotic factors affecting sulfur oxidation in soils, showing a parabolic relationship where oxidation is minimal at low moisture, increases as moisture approaches an optimal level (around 60% of field capacity) and peaks before declining. Soil moisture is affected by factors like soil type, texture and aeration, with adequate aeration being vital for the growth of sulfur-oxidizing bacteria, as poor aeration can impair their development and reduce sulfur oxidation rates (Pourbabaee et al., 2020).
     
    Land cultivation and agronomic practices
     
    Conventional tillage can lead to a swift reduction in soil organic matter, resulting in decreased sulfur levels and diminished long-term fertility of the soil. Soils that are regularly treated with Sulfur show a higher count of Thiobacillus spp., which suggests a greater potential for Sulfur oxidation compared to soils that have never been treated with Sulfur, indicating a priming effect from the oxidation by Thiobacillus spp. This type of soil also influences the rate of sulfur oxidation. Typically, sulfur oxidation occurs at a higher rate in sandy loam, followed by clay soil, while it is significantly lower in silty clay soil (Malik et al., 2021).
     
    Crop and cropping system
     
    As demonstrated in fallow fields, the type of crop and cropping system plays a significant role in influencing sulfur transformations within the soil, primarily because of the heightened microbial biomass present in the rhizosphere. Implementing cropping techniques that minimize nutrient loss and enhance soil organic matter could be beneficial for increasing the availability of sulfur in the soil during years conducive to mineralization, all while reducing the dependency on added fertilizer sulfur (Iannucci et al., 2021).
     
    Soil microbes
     
    Soil microorganisms play a crucial role in transforming reduced sulfur compounds in the soil into a form that can be absorbed (SO42"). While many microorganisms participate in sulfur oxidation, bacteria, particularly Thiobacillus and related species, have a significant effect on this process (Rana et al., 2020). The quantity and activity of microbial biomass affect the rate at which elemental sulfur is oxidized in agricultural soils. The oxidation of sulfur in soil is primarily carried out by heterotrophic sulfur-oxidizing groups, with autotrophic microorganisms following behind. A large proportion of organic sulfur in the soil exists as sulfate esters (up to 60%), which can be readily mineralized through the action of enzymes produced by a wide range of heterotrophic bacteria, including Pseudomonas and Thiobacillus species (Rana et al., 2020). Certain microbial species or genera within a crop’s rhizosphere have a more significant influence on sulfur cycling than others found in the crop itself. However, due to the fact that most soil microorganisms cannot be cultivated in artificial media, this functional specialization has been largely overlooked. As a result of this limitation, cultivation-based methods offer a distorted view of microbial ecology in the soil. To gain a better understanding of the involvement of soil microorganisms in sulfur cycling, a targeted investigation into functional diversity is necessary. This can be achieved through cultivation-independent techniques like stable isotope probing and soil genetic profiling (Alcolombri et al., 2022; Dumont and Hernández García,  2019).
     
    Particle size
     
    Effective oxidation requires that A. thiooxidans come into direct contact with Sp  particles (Ranadev et al., 2023). To enhance the effectiveness of sulfur fertilizer (Sp ), the particle size of applied sulfur should ideally fall between 80 and 1000 mesh or be even finer.
     
    Soil organic matter
     
    Organic carbon and soil organic matter have a significant positive relationship with soil sulfur. Organic sulfur comprises a varied array of soil microorganisms and partially decomposed remains of plants, animals and microbes, which accounts for about 95% of the total sulfur found in most agricultural soils (Kodavali and Khurana, 2022). Fresh organic sulfur decomposes more quickly than older organic sulfur, which is released at a slower rate. Organic materials such as wheat straw, broom grass clippings, farmyard manure, poultry litter and peat moss have been found to enhance soil sulfur levels (Lee et al., 2021; Malik et al., 2021).
     
    Prospects for the future in Agriculture
     
    The use of SOB extends beyond agriculture and encompasses a variety of other sectors. In environmental science, they are vital in neutralizing H2S, remediating soil and treating wastewater. Furthermore, with the current focus on nanotechnology, SOB is employed in the creation of nanoscale sulfide particles that exhibit superior optical, electronic and mechanical attributes compared to other metal nanoparticles. Furthermore, SOB is crucial for increasing the operational lifespan of bio-electrochemical fuel cells, particularly sediment microbial fuel cells (SMFC), by reducing phosphorus discharge from the sediment, thereby supporting electrical current production. SOB thrives in extreme environmental settings, including high salinity regions (halophytes) and acidic soils (acidophilic), offering extensive genetic variation that can be utilized to tackle various challenges in agriculture and other scientific disciplines through biotechnological methods. Despite its potential, the low biomass of SOB, the acidification of the process solution and the selectivity of Bio-S0 hinder its industrial use. Consequently, additional efforts must be made to enhance the BDS process for industrial purposes through various research avenues. In the energy field, researchers are utilizing cellulose nanofiber derived from SOB to enhance lithium-sulfur batteries (LSBs). In the field of metallurgy, the bioleaching of different metals, including Cu, Zn and Fe, using SOB proves to be cost-effective. At present, CRISPR-Cas is a widely used method for genome editing. This system can be employed to create genetically modified SOB with improved thermostability, solvent resistance and broader substrate specificity, facilitating better utilization of SOB in agriculture and other sectors.

    CONCLUSION

    A growing number of soils around the globe are experiencing sulfur deficiency, which can result in lower crop productivity and yield declines. In India, about 46% of soils lack adequate sulfur, causing crop yields to drop by 20% to 40%. Similar observations have been reported from various regions worldwide. Although sulfur exists primarily in organic forms in most soils, it is not easily accessible for plants to absorb. Utilizing S0 presents a cost-effective option for swiftly restoring sulfur levels, but it requires oxidation to sulfate for plant uptake. The oxidation efficiency of S0 in soil is affected by various soil and environmental factors, along with the particle size of sulfur and the diversity of soil microorganisms. The biotechnological use of sulfur-oxidizing bacteria (SOB) provides a chance to create innovative biofertilizers and enhance the sulfur oxidation process in soil. While there has been evidence of the positive impacts of sulfur combined with SOB on crop growth and yields, research in this area is still limited and the persistence of SOB in different formulations has not been investigated. Additionally, SOB has several traits that promote plant growth, such as the production of IAA, siderophores, antimicrobial substances and ACC deaminase activity, which can be utilized as beneficial properties in biofertilizers. Additional research is required to explore and examine the different biochemical pathways involved in sulfur oxidation across various soils in diverse agroclimatic regions.

    CONFLICT OF INTEREST

    The authors declare no commercial or financial conflict of interest.

    REFERENCES


    1. Alcolombri, U., Pioli, R., Stocker, R. and Berry, D. (2022). Single-cell stable isotope probing in microbial ecology. ISME communi- cations. 2(1): 55.

    2. Anandham, R., Gandhi, P.I., Madhaiyan, M. and Sa, T. (2008a). Potential plant growth promoting traits and bioacidulation of rock phosphate by thiosulfate oxidizing bacteria isolated from crop plants. Journal of Basic Microbiology. 48(6): 439-447.

    3. Anandham, R., Gandhi, P.I., SenthilKumar, M., Sridar, R., Nalayini, P. and Sa, T.M. (2011). Sulfur-oxidizing bacteria: A novel bioinoculant for sulfur nutrition and crop production. Bacteria in agrobiology: Plant Nutrient Management. pp. 81-107.

    4. Anandham, R., Indira Gandhi, P., Kwon, S. W., Sa, T.M. and Jee, H.J. (2009a). Taxonomic characterization of facultative chemolithoautotrophic strains ATSB16 isolated from rhizosphere soils. International workshop on microbial sulfur metabolism. March-15-18. Tomar, Portugal. pp. 151.

    5. Anandham, R., Indira Gandhi, P., Kwon, S.W., Sa, T.M., Kim, Y.K. and Jee, H.J. (2009b). Mixotrophic metabolism in Burkholderia kururiensis subsp. thiooxydans subsp. nov., a facultative chemolithoautotrophic thiosulfate oxidizing bacterium isolated from rhizosphere soil and proposal for classification of the type strain of Burkholderia kururiensis as Burkholderia kururiensis subsp. kururiensis subsp. nov. Archives of Microbiology. 191: 885-894.

    6. Anandham, R., Indiragandhi, P., Kwon, S.W., Sa, T.M., Jeon, C.O., Kim, Y.K. and Jee, H.J. (2010). Pandoraea thiooxydans sp. nov., a facultatively chemolithotrophic, thiosulfate-oxidizing bacterium isolated from rhizosphere soils of sesame (Sesamum indicum L.). International Journal of Systematic and Evolutionary Microbiology. 60(1): 21-26.

    7. Anandham, R., Indiragandhi, P., Madhaiyan, M., Ryu, K.Y., Jee, H.J. and Sa, T.M. (2008b). Chemolithoautotrophic oxidation of thiosulfate and phylogenetic distribution of sulfur oxidation gene (soxB) in rhizobacteria isolated from crop plants. Research in Microbiology. 159(9-10): 579-589.

    8. Anandham, R., Sridar, R., Nalayini, P., Madhaiyan, M., Gandhi, P.I., Choi, K.H. and Sa, T.M. (2005). Isolation of sulfur oxidizing bacteria from different ecological niches. Korean Journal of Soil Science and Fertilizer. 38(4): 180-187.

    9. Anandham, R., Sridar, R., Nalayini, P., Poonguzhali, S. and Madhaiyan, M.J.M.R. (2007). Potential for plant growth promotion in groundnut (Arachis hypogaea L.) cv. ALR-2 by co-inoculation of sulfur-oxidizing bacteria and Rhizobium. Microbiological Research. 162(2): 139-153.

    10. Assefa, S., Haile, W. and Tena, W. (2021). Effects of phosphorus and sulfur on yield and nutrient uptake of wheat (Triticum aestivum L.) on Vertisols, North Central, Ethiopia. Heliyon. 7(3).

    11. Balagangathar, K., Kalaiyarasan, C., Kandasamy, S., Madhavan, S. and Jawahar, S. (2024). Impact of nitrogen and sulphur application on the growth and yield of groundnut (Arachis hypogeae L.). Crop Research. 59(3,4): 138-142.

    12. Beijerinck, M. W. (1904). Phenomenes de reduction produits par les microbes. Archives Neerlandaises des Sciences Exactes et Naturelles. 2(13): 1-157.

    13. Blum, S. C., Lehmann, J., Solomon, D., Caires, E.F. and Alleoni, L.R.F. (2013). Sulfur forms in organic substrates affecting S mineralization in soil. Geoderma. 200: 156-164.

    14. Bounaga, A., Alsanea, A., Lyamlouli, K., Zhou, C., Zeroual, Y., Boulif, R. and Rittmann, B.E. (2022). Microbial transformations by sulfur bacteria can recover value from phosphogypsum: A global problem and a possible solution. Biotechnology Advances. 57: 107949.

    15. Bouranis, D.L., Malagoli, M., Avice, J.C. and Bloem, E. (2020). Advances in plant sulfur research. Plants. 9(2): 256.

    16. Camberato, J. and Casteel, S. (2017). Sulfur deficiency. Purdue Univ. Dep. of Agronomy, Soil Fertility Update.

    17. Chaudhary, S., Dhanker, R., Kumar, R. and Goyal, S. (2022). Importance of legumes and role of Sulphur oxidizing bacteria for their production: A review. Legume Research-An International Journal. 45(3): 275-284. doi: 10.18805/LR-4415.

    18. Dahl, C. (2020). A biochemical view on the biological sulfur cycle. Environmental technologies to treat sulfur pollution: Principles and Engineering. 2: 55-96.

    19. Das, S., Khanam, R., Bag, A.G., Chatterjee, N., Hazra, G.C., Kundu, D. and Ghouse, S.K.P. (2022). Spatial distribution of sulphur and its relationship with soil attributes under diverse agro- climatic zones of West Bengal, India. Journal of the Indian Society of Soil Science. 69(4): 401-410.

    20. Dumont, M. G. and Hernández, M. (2019). Stable isotope probing. Methods and Protocols Totowa, NJ, US: Humana Press.

    21. Fujita, Y. and Uesaka, K. (2022). Nitrogen fixation in cyanobacteria. Cyanobacterial Physiology. pp. 29-45.

    22. Germida, J.J., Wainwright, M. and Gupta, V.V. (2021). Biochemistry of sulfur cycling in soil. In Soil biochemistry. CRC Press. pp. 1-53.

    23. Harborne, A.R., Rogers, A., Bozec, Y.M. and Mumby, P.J. (2017). Multiple stressors and the functioning of coral reefs. Annual Review of Marine Science. 9(1): 445-468.

    24. He, Y., Zeng, X., Xu, F. and Shao, Z. (2022). Diversity of mixotrophic neutrophilic thiosulfate-and iron-oxidizing bacteria from deep-sea hydrothermal vents. Microorganisms. 11(1): 100.

    25. Iannucci, A., Canfora, L., Nigro, F., De Vita, P. and Beleggia, R. (2021). Relationships between root morphology, root exudate compounds and rhizosphere microbial community in durum wheat. Applied Soil Ecology. 158: 103781.

    26. Kang, E., Li, Y., Zhang, X., Yan, Z., Wu, H., Li, M. and Kang, X. (2021). Soil pH and nutrients shape the vertical distribution of microbial communities in an alpine wetland. Science of the Total Environment. 774: 145780.

    27. Kazemi, E., Soofiyani, S.R., Ahangari, H., Eyvazi, S., Hejazi, M.S. and Tarhriz, V. (2021). Chemolithotroph Bacteria: From biology to application in medical sciences. Crescent Journal of Medical and Biological Sciences. 8(2).

    28. Khan, B.A., Hussain, A., Elahi, A., Adnan, M., Amin, M.M., Toor, M.D. and Ahmad, R. (2020). Effect of phosphorus on growth, yield and quality of soybean (Glycine max L.): A review. International Journal of Advanced Research. 6(7): 540-545.

    29. Khasimov, M.K., Laurinavichene, T.V., Petushkova, E.P. and Tsygankov, A.A. (2021). Relations between hydrogen and sulfur metabolism in purple sulfur bacteria. Microbiology. 90: 543-557.

    30. Kodavali, M.R. and Khurana, M.P.S. (2022). Sulphur and its significance in higher pulse production. Environment Conservation Journal. 23(3): 367-373.

    31. Kong, Y.H., Ren, W.T., Xu, L., Cheng, H., Zhou, P., Wang, C.S. and Xu, X.W. (2022). Mesobacterium pallidum gen. nov., sp. nov., Heliomarina baculiformis gen. nov., sp. nov. and Oricolaindica sp. nov., three novel Alphaproteobacteria members isolated from deep-sea water in the southwest Indian ridge. International Journal of Systematic and Evolutionary Microbiology. 72(2): 005236.

    32. Kulczycki, G. (2021). The effect of elemental sulfur fertilization on plant yields and soil properties. Advances in Agronomy. 167: 105-181.

    33. Kumar, M., Zeyad, M.T., Choudhary, P., Paul, S., Chakdar, H. and Rajawat, M.V.S. (2020). Thiobacillus. In Beneficial microbes in agro-ecology. Academic Press. pp. 545-557.

    34. Lee, S.Y., Kim, E.G., Park, J.R., Ryu, Y.H., Moon, W., Park, G.H. and Kim, K.M. (2021). Effect on chemical and physical properties of soil each peat moss, elemental sulfur and sulfur-oxidizing bacteria. Plants. 10(9): 1901.

    35. Malik, K.M., Khan, K.S., Billah, M., Akhtar, M.S., Rukh, S., Alam, S. and Khan, N. (2021). Organic amendments and elemental sulfur stimulate microbial biomass and sulfur oxidation in alkaline subtropical soils. Agronomy. 11(12): 2514.

    36. Narayan, O.P., Kumar, P., Yadav, B., Dua, M. and Johri, A.K. (2023). Sulfur nutrition and its role in plant growth and development. Plant Signaling and Behavior. 18(1): 2030082.

    37. Noman, H.M., Rana, D.S., Choudhary, A.K., Dass, A., Rajanna, G.A. and Pande, P. (2020). Improving productivity, quality and biofortification in groundnut (Arachis hypogaea L.) through sulfur and zinc nutrition in alluvial soils of the semi-arid region of India. Journal of Plant Nutrition. 44(8): 1151-1174.

    38. Nosalova, L., Piknova, M., Kolesarova, M. and Pristas, P. (2023). Cold sulfur springs-neglected niche for autotrophic sulfur- oxidizing bacteria. Microorganisms. 11(6): 1436.

    39. Nyamath, S., Subburamu, K., Kalyanasundaram, G.T., Balachandar, D., Suresh, M. and Anandham, R. (2024). Multifarious characteristics of sulfur-oxidizing bacteria residing in rice rhizosphere. Folia Microbiologica. 69(2): 395-405.

    40. Park, S., Kim, H.W., Joo Lee, C., Kim, Y. and Sung, J. (2024). Profiles of volatile sulfur compounds in various vegetables consumed in Korea using HS-SPME-GC/MS technique. Frontiers in Nutrition. 11: 1409008.

    41. Pourbabaee, A.A., Koohbori Dinekaboodi, S., Seyed Hosseini, H.M., Alikhani, H.A. and Emami, S. (2020). Potential application of selected sulfur-oxidizing bacteria and different sources of sulfur in plant growth promotion under different moisture conditions. Communications in Soil Science and Plant Analysis. 51(6): 735-745.

    42. Ramamoorthy, P. and Ariraman, R. (2023). Effect of phosphorus and sulphur application on growth, yield attributes, nutrient uptake, quality and economics of blackgram (Vigna mungo L.): A review. Agricultural Reviews. 44(2): 252-258. doi: 10.18805/ag.R-2180.

    43. Rameez, M.J., Pyne, P., Mandal, S., Chatterjee, S., Alam, M., Bhattacharya, S. and Ghosh, W. (2021). Two pathways for thiosulfate oxidation in the alphaproteobacterial chemolithotroph Paracoccus thiocyanatus SST. Microbiological Research. 230: 126345.

    44. Rana, K., Rana, N. and Singh, B. (2020). Applications of sulfur oxidizing bacteria. In Physiological and biotechnological aspects of extremophiles. Academic Press. pp. 131-136.

    45. Ranadev, P., Revanna, A., Bagyaraj, D.J. and Shinde, A.H. (2023). Sulfur oxidizing bacteria in agro ecosystem and its role in plant productivity-a review. Journal of Applied Micro- biology. 134(8): 161.

    46. Shah, S.H., Islam, S. and Mohammad, F. (2022). Sulphur as a dynamic mineral element for plants: A review. Journal of Soil Science and Plant Nutrition. 22(2): 2118-2143.

    47. Sharma, A.K., Samuchia, D., Sharma, P.K., Mandeewal, R.L., Nitharwal, P.K. and Meena, M. (2022). Effect of nitrogen and sulphur in the production of the mustard crop [Brassica juncea (L.)]. International Journal of Environment and Climate Change. 12: 132-137.

    48. Sharma, J., Dua, V.K., Sharma, S., Choudhary, A.K., Kumar, P. and Sharma, A. (2022). Role of plant nutrition in disease development and management. In Sustainable Management  of Potato Pests and Diseases. Singapore: Springer Singapore. pp. 83-110.

    49. Singh, N., Kushwaha, H.S. and Singh, A. (2020). Integrated nutrient management on growth, yield, nutrient uptake and fertility balance in soybean (Glycine max L.)-wheat (Triticum aestivum L.) cropping sequence. International Journal of Bio-resource and Stress Management. 11(4): 405-413.

    50. Singh, R.P., Singh, S.K., Yadav, P.K. and Singh, S.N. (2010). Effect of sulphur and calcium on yield and quality of mustard (Brassica juncea).

    51. Skwierawska, M., Benedycka, Z., Jankowski, K. and Skwierawski, A. (2016). Sulphur as a fertiliser component determining crop yield and quality. Journal of Elementology. 21(2): 609-623. doi: 10.5601/jelem.2015.20.3.992.

    52. Slocum, R.D. and Flores, H.E. (2024). Biochemistry and physiology of polyamines in plants. CRC press.

    53. Stamford, N.P., Figueiredo, M. V., da Silva Junior, S., Freitas, A.D.S., Santos, C.E.R. and Junior, M.A.L. (2015). Effect of gypsum and sulfur with Acidithiobacillus on soil salinity alleviation and on cowpea biomass and nutrient status as affected by PK rock biofertilizer. Scientia Horticulturae. 192: 287-292.

    54. Stamford, N.P., Silva Junior, S.D., Rosália, C.E.D., Santos, S., Freitas, A.D.S.D., Lira Júnior, M. D. A. and Barros, M.D.F.C. (2013). Cowpea nodulation, biomass yield and nutrient uptake, as affected by biofertilizers and rhizobia, in a sodic soil amended with Acidithiobacillus. ActaScientiarum. Agronomy. 35: 453-459.

    55. Stellhorn, J.R., Hayakawa, S., Klee, B.D., Paulus, B., Link Vasco, J., Rinn, N. and Pilgrim, W. C. (2022). Local structure of amorphous organotin sulfide clusters by low energy X ray absorption fine structure. Physica Status Solidi (b). 259(9): 2200088.

    56. Tabak, M., Lisowska, A., Filipek-Mazur, B. and Antonkiewicz, J. (2020). The effect of amending soil with waste elemental sulfur on the availability of selected macro elements and heavy metals. Processes. 8(10): 1245.

    57. Valle, S.F., Giroto, A.S., Klaic, R., Guimaraes, G.G. and Ribeiro, C. (2019). Sulfur fertilizer based on inverse vulcanization process with soybean oil. Polymer Degradation and Stability. 162: 102-105.

    58. Velu, G., Palanichamy, V. and Rajan, A.P. (2018). Phytochemical and pharmacological importance of plant secondary metabolites in modern medicine. Bioorganic Phase in Natural food: An Overview. pp. 135-156.

    59. Watling, H.R., Johnson, J.J., Shiers, D.W., Gibson, J.A.E., Nichols, P.D., Franzmann, P.D. and Plumb, J.J. (2016). Effect of temperature and inoculation strategy on Cu recovery and microbial activity in column bioleaching. Hydrometallurgy. 164: 189-201.

    60. Wen, Y.M., Wang, Q.P., Tang, C. and Chen, Z.L. (2012). Bioleaching of heavy metals from sewage sludge by Acidithiobacillus thiooxidans-a comparative study. Journal of Soils and Sediments. 12: 900-908.

    61. Yousuf, B., Kumar, R., Mishra, A. and Jha, B. (2014). Unravelling the carbon and sulphur metabolism in coastal soil ecosystems using comparative cultivation-independent genome-level characterization of microbial communities. PLoS One. 9(9): e107025.

    62. Zenda, T., Liu, S. Dong, A. and Duan, H. (2021). Revisiting Sulphur - The once neglected nutrient: It’s roles in plant growth, metabolism, stress tolerance and crop production. Agriculture. 11(7): 626.

    63. Zhang, Y., Wang, Q., Rogers, M. J. and He, J. (2025). Autotrophic denitrification under anoxic conditions by newly discovered mixotrophic sulfide-oxidizing bacterium. Bioresource Technology. pp. 132553.

    64. Zhao, C., Wang, J., Zang, F., Tang, W., Dong, G. and Nan, Z. (2022). Water content and communities of sulfur-oxidizing bacteria affect elemental sulfur oxidation in silty and sandy loam soils. European Journal of Soil Biology. 111: 103419.
    In this Article
      Contact us
      Follow us
      Published In
      Agricultural Reviews

      Editorial Board

      View all (0)