The concept of probiotics has a very long history. It is associated with the consumption of fermented foods by human beings. The earliest types of probiotic foods includes dairy products fermented by lactic acid bacterial (LAB) and fungal fermentation, leavened bread fermented by yeasts and cheeses (
Kopp-Hoolihan, 2001). A wide variety of probiotic products are available in market
viz. food or dairy products, infant foods, dietary supplements, beverages, livestock feeds and fish feeds (
Parvez, 2006), a swift emergence of the wave of pharmaceutical probiotic products was earlier projected
(Sanders et al., 2003). The probiotics are contributing in the cosmetics. Nondairy and horticulture products are also used as a delivery media for probiotics (
Sreeja and Prajapati, 2016).
The probiotics can modulate the gut microflora and improve the health status of the consumers. Similarly, the administration of probiotics in the feed stuffs of livestock and fishes leads to modulate the intestinal microbiotia leading to efficient digestion and assimiliation of feeds. There is a lack of knowledge about probiotics that are used as feed additives, mainly because research is mainly focused on human nutrition. Probiotic mechanisms that modify the conversion of nutrients also need to be discussed
(Simon et al., 2001). Studies have demonstrated beneficial impact on reestablishment of friendly microbiota through different mechanisms such as appropriate intestinal homeostasis (
Wilkins and Sequoia 2017). A consortium based approach wherein different strains from various genera of the proven probiotic organisms has been advocated
(Timmerman et al., 2004, Mohammed et al., 2022).
Probiotics in food/ dairy products
Food industry is constantly evolving entailing innovation phenomena that generate constant research and emerging technologies. The change of consumers’ preferences, needs and acceptance is a dynamic process, hence the maintenance of food quality
via technology-driven innovation is evident
(Savino et al., 2018). The cultural heritage of consumers, habits and even sustainability factors can similarly affect technology innovations applied in the food industry
Martin-Rios et al. (2018). Nowadays, consumers are becoming more health conscious and concerned about the beneficial value of food, directing manufacturers to emphasize on the promotion of functional foods. A key for successful marketing and acceptance of novel foods depends not only on the concept of food quality throughout the chain but also to added value food functionalities
(Khedkar et al., 2017). These organisms when administered in defined quantitative and qualitative amount will provide clinically proven health benefits apart from those delivered by fundamental nutrients in the product in question (
Brown, 2018).
Food products containing probiotics can carry a single or many different bacterial strains. Specifically, in fermented food products, probiotics can be added as starter cultures while other bacterial or yeast strains co-exist. Food-based probiotic products account for a large number of formulations and can be divided in two distinct categories: Dairy products
dahi, cheese, ice-cream, yoghurt,
etc. and non-dairy products,
e.g., meats and meat products, bread or other fiber snacks, chocolates, fruit juices and fruit preparations. The vast availability of food products makes them a good and potentially effective carrier system for the delivery of probiotics. Nevertheless, their ability to deliver
viable cells to the human intestine may differ considerably, depending largely on the physicochemical properties of each composite food matrix
(Antonia et al., 2019). Consumption of probiotic bacteria through dairy food products is an ideal way to re-establish the balance of intestinal microflora. It must conform to certain requirements for a dairy food product to be considered as a valuable alternative for delivery of probiotic bacteria on one hand and for variety of probiotic cultures to use as a dietary adjunct and to exert a positive influence in the other hand
(Homayouni et al., 2008). It is not out of place to mention that the importance to report that probiotic bacteria should be present in a dairy food to a minimum level of 106 CFU/g or the daily intake should be about 108 CFU/g, with the aim to compensate for the possible reduction in the number of these vital microbes during the passage through the gut (
Shah, 2007).
Probiotics in dietary supplements
The concept of functional foods has been evolved recently after extensive research to find out the role of nutrients on health (
Gibson, 2007). It contains physiologically active components, which provide health benefits beyond basic nutrition by affecting one or more functions in the body in a targeted way
(Anjuman et al., 2015). A dietary supplement is an orally administered substance designed to deliver a certain dietary ingredient to complement the diet (
Sharma and Devi, 2014 and
Thomas and Greer, 2010). These active ingredients are usually packaged in different forms of capsules, tablets, powders (in sachets) or liquids in measured doses (
Webb, 2011 and
Klayraung, et al., 2009). Probiotics must be able to tolerate the severe conditions of gastrointestinal tract and arrive
viable to the site of action (
Bansal and Garg, 2008). The manufacturing process of a dietary supplement is similar to medicines; however, the severe courses of action used in medicinal products are not necessary to pursue (
Amaral, 2014). A strong negative correlation between bacterial
viability and compression force has been observed, revealing that probiotic survival decreases
via increasing the tablet compaction forces
(Silva et al., 2013). Apart from food, we can add probiotics to our diet through dietary supplements. These are not drugs, so they do not need to be approved by the food (Federal) and drug administration (FDA).
Probiotics in infant feeding
A systematic review concluded that probiotics may be beneficial in preventing eczema in infants
(Zuccotti et al., 2015). However, another study found probiotics to be a significant risk factor for vancomycin-resistant
Enterococcus colonization and was suggested to mediate the acquisition and transfer of resistance genes of bacteria
(Topcuoglu et al., 2015). Despite this, surveys have shown that clinicians and naturopaths recommend probiotic consumption for patients with a variety of pathologies including diarrhea, ulcerative colitis and infant colic due to their low cost, over-the-counter availability and acceptable safety profile in healthy adults
(Abe et al., 2013 and
Gasbarrini et al., 2015). There is a lack of evidence that the probiotics influence the gut microbiome when given exogenously and their effect on health outcomes in infants are largely unknown
(Quin et al., 2018).
Reports on the colonizing capability of
Lactobacillus GG have varied
(Agarwal et al., 2003). About 86% colonization rate was reported in a randomized controlled trial of
L. acidophilus. In Columbia, the prophylactic administration of
L. acidophilus and Bif. infantis to all neonates in an intensive care nursery with a high incidence of NEC reduced the incidence of disease compared with historical controls
(Dani et al., 2002).
Probiotics in pharmaceutical preparations
The use of probiotics is a new way to control and treat infections in this modern era (
Sreeja and Prajapati, 2016). A wide range of probiotic products is available in the market and can be easily purchased over the counter and unlike pharmaceutical drugs, their commercial distribution is not strictly regulated. Several systems have been developed for the delivery of probiotics to the GIT such as pharmaceutical formulations and food-based products. Pharmaceutical preparations in particular are considered more effective compared to commercial food-based carrier systems although their preference mainly depends on consumers’ perception
(Khedkar et al., 2017). Examples of pharmaceuticals for the delivery of probiotics currently include, capsules, liquids, powder beads, ampoules and tablets (
Sokol et al.,2008). Strain selection and differentiation is considered a crucial step in both pharmaceutical and food systems. Likewise, an issue that needs evaluation is the method of preparation of the delivery matrix which may affect cell
viability and effective target release in the GIT (
Antonia et al.,2019). Some of the spore-forming strains of Bacillus are marketed commercially as they survive harsh gastrointestinal conditions and bestow health benefits to the host
(Khatri et al., 2019). Clinical practitioners use probiotic pharma products mostly as supplements (
Sreeja and Prajapati, 2016).
Sarowska et al., 2013, Lakra and Krishnani, 2022 sowed the exact mechanism of action of probiotics has not been explained, but a number of aspects, the way it affects the human body was found and summarized.
Probiotics in beverages
The relationship between increased number of beneficial bacteria in gut and its biological effects are yet to be elucidated
(Plaza-Diaz et al., 2015). The study by
Hassan et al. (2012) showed rice and millet grains were fermented with ABT-2 starter culture (
Str. Thermophilus, L. acidophilus and
Bifidobacterium BB-12) to obtain probiotic beverages, fortified with pumpkin and sesame seed milk in order to combine the high nutritive value of seeds and the health benefits of the probiotic culture. The levels of several factors,
i.e. starter culture concentration, rice and millet level and the amount of honey, affecting the fermentation process, were established for completing a controlled fermentation for 16 h. At the end of fermentation the
viable cell counts reached to about 4.3x10 cfu/ml. Changes were observed in acidity and counts of probiotic bacteria as a result of fortification with pumpkin and sesame milk at 10%. The shelf-life of the rice and millet fermented beverages was estimated to be 15 days under refrigerated storage
(Amal et al., 2012).
There is also an increased demand for the probiotic containing vegetarian products. Furthermore, lactose intolerance and the cholesterol content are two major drawbacks related to the fermented dairy products (
Heenan et al, 2004;
Yoon et al., 2006). There is a wide variety of traditional non-dairy fermented beverages produced around the world. Much of them are non-alcoholic beverages manufactured with cereals as principal raw material. The non dairy probiotic beverages may be made from a variety of raw materials, such as cereals, millets, legumes, fruits and vegetables. Studies may be classified based on the source of raw material for the production of the non dairy probiotic beverage (
Vasudha and Mishra, 2013).
Probiotics in cosmetic products
The concept of “probiotics” in cosmetics is defined as living microorganisms and/or their lysates, application of which in cosmetic products in adequate amount confer a positive effect on the human skin in addition to the characteristic of the main influence of the product (
Tkachenko et al. 2017). According to the FDA, a cosmetic is defined as “a product (excluding pure soap) intended to be applied to the human body for cleansing, beautifying, promoting attractiveness, or altering the appearance”. The use of beneficial microbes for this purpose has seen the field of probiotics grow substantially
(Hill et al., 2014). The probiotic applications range widely in type, scope and applications including cosmetics. There are numerous studies providing evidence of the benefits of specific probiotic strains for skin health
(Yu et al., 2020). In addition, the mechanisms of anti-ageing suggest that some strains can help to regulate pH, reduce oxidative stress, protect from photo ageing and improve the skin barrier function (
Sharma, 2016). Due to safety concerns, cosmetic products are expected to have a low content of microorganisms (below 500 cfu/g for eye-area products and 1000 cfu/g for the rest). Applications for skin care require local use
(Tkachenko, et al., 2017). Orally administered probiotics have demonstrated to improve the intestinal microbiome leading to a potential improvement in skin conditions such as atopic dermatitis, acne, orrosacea
(Knackstedt et al., 2020).
Probiotics in cattle feeds
The effect of probiotics was linked to the gastrointestinal tract and on incidence of diarrhea and other gut infections. However, the earlier research findings showed that the effects of probiotics may be more general (
Fuller, 1992 and
Cho et al., 2011). In general, the mode of action of probiotic feed additives is mainly based on competitive exclusion, bacterial antagonism and immune modulation (
Hughes and Heritage, 2002). The use of probiotics in animal feeds could be enhanced by a preliminary
in vitro screening of the candidate organisms for its antimicrobial activity, survival in the gut, adhesion studies and antibiotic susceptibility. The analyses of phenotypic and genetic properties are also useful for industrial production
(Gaggia et al., 2010). Dose, timing and duration of administration of the probiotics may be a factor affecting efficacy
(Sazawal et al., 2006 and
Rosenfeldt et al., 2003). Another determinant is the age of the animals; during early life, colonization patterns are instable and the animals are susceptible to environmental pathogens. Probiotics have been proposed as a
viable alternative to antimicrobials to enhance animal health and productivity (
Markowiakand Slizewska, 2018). Effect of probiotics on disease prevention and performance indicators and host target system microbiota are yet to be quantified and documented
(Siggers et al., 2007).
Probiotics in poultry feeds
Probiotics have a beneficial effect on health that stimulates the growth of friendly microorganisms and reduces/eliminates the population of pathogens, thus improving the intestinal microbial balance and lowering the risk of gastro-intestinal diseases.
Markowiak and Slizewska (2018) reported that the role of probiotics in protection against the pathogens. An accurate dosage of administration has yet to be established despite the widespread use of probiotics. Probiotics have antimutagenic, anticarcinogenic, hypocholesterolemic, antihypertensive, anti-osteoporosis and immunomodulatory effects in poultry birds.
Lactobacillus, Bifidobacterium, Leuconostoc, Enterococcus, Lactococcus, Bacillus, Saccharomyces, Aspergillus and
Pediococcus species are most commonly used probiotics in poultry production. The probiotics improve feed-intake, growth performance, meat quality, egg production, egg quality and have cholesterol lowering potential in poultry products. However, some studies reported no significant effect of probiotics on feed-intake, production traits, product quality and cholesterol level (
Tarekegn, 2016). Probiotics are widely accepted as an alternative to in-feed antibiotics in poultry production. A probiotic containing novel strain such as
Aspergillus oryzae is also in practice, but its effect on performance of poultry is limited
(Lee et al., 2006). The ban on the use of antibiotic growth promotors in many countries in order to satisfy the consumers’ demands for healthy and safe meat leads to increasing researchers’ interest in finding strategies to maintain chicken health and production. The use of probiotics in poultry diets has been associated with positive effects on health and growth in birds. Changes in growth performance often affect various meat quality traits and in this context, using probiotics as dietary supplements exhibit potential as a natural way to improve poultry meat quality (
Popova, 2017). The addition of probiotics to the feed improves growth performance and feed conversion in broilers and egg mass, egg weight and egg size in layers (Fig 1). This is attributed to (i) maintaining normal intestinal microflora by competitive exclusion and antagonism, (ii) altering metabolism by increasing digestive enzyme activity and decreasing bacterial enzyme activity and ammonia production, (iii) improving feed intake and digestion and (iv) neutralizing enterotoxins and stimulating the immune system
(Jin et al., 2019).
Probiotics in aquafeed
Aquaculture is an important food producing sector to fulfill nutritional food demand of a continuously growing population. However, disease outbreak has become a major problem in aquaculture which causes huge economic loss to aquaculture industries. The use of expensive chemotherapeutic drugs has negative impact on the aquatic environment. So there is a growing concern to find other safe, non-antibiotic based and eco-friendly alternative for the treatment of the diseases
(Muziri et al., 2022). The use of probiotics is a promising alternative approach for the control and treatment of infectious agents and stimulation of growth, improved digestion, enhanced immune response and recuperate the water quality as well. Probiotics strengthen the fish to fight against various pathogens and improves the overall health as they show anti-bacterial, anti-fungal and anti-viral properties. The fish consuming probiotics absorb minerals and vitamins easily and in large amounts than average. Instead of using antibiotics as a treatment when the sickness is already there, it is much safer and cost-effective in all ways to use probiotics. The use of probiotics in aquaculture is a recent trend and its efficacy in aquatic environment has not been studied extensively (
Chauhan and Singh, 2019). In shrimp/fish aquaculture, feed represents the most expensive production cost. The quantity and quality of diets are primary factors influencing shrimp/fish growth, health status, disease prevention, pond contamination and expenses. Utilization of probiotic bacteria has emerged as a solution with enormous applications in the aquafeed industry. The various routes of administration of probiotics and mechanism of action are shown in Fig 2 and 3. Bacillus species, principally
B. subtilis are one of the most investigated bacteria due to: a) versatility of growth nutrients utilization, b) high level of enzymes production, c) secretion of antimicrobial compounds, d) spore producers, e) develops in aerobic and anaerobic conditions and f)
B. subtilis is a GRAS. Functional feeds development with alternative economic nutrients and vegetable sources of proteins, carbohydrates, lipids and
Bacillus subtilis probiotic strains, must be considered in shrimp/fish aquaculture production systems. This is an option to eliminate animal feed ingredients, improves digestion-assimilation, reduce water pollution and diseases and to increase yields and profits (
Olmosand and Paniagua, 2014).
