Dam water
We deduced that the temperature measured at the surface was high, it reached 19.6°C compared to that measured at 30 meters which reached 16.3°C (Table 1). We noticed that the turbidity of 30 m was very high exceeding the Algerian standards (5 UTN) has a value which reached 17.6, higher than the turbidity measured on the surface (3.32 UTN). It was assumed that the increase in turbidity was due to bottom cleaning. The measured hydrogen potential was in the Algerian standards (6.5-9), estimated at 7.6 in surface water and 8.36 at the depth of 30 meters of water. According to the results obtained, it was noted that the value of the conductivity estimated at 505 µs\cm at the surface was lower than that measured at 30m depth (509 µs\cm). The dissolved oxygen at the surface was higher than that at the bottom with a value of 10.6 at the surface and 8.75 at 30 meters depth.
Bacteriological parameters of the water
We have noticed that on PCA medium at 22°C, the number of colonies of psychrophilic germs was in descending order from 161 to 98 colonies. On PCA medium at 37°C, the number of colonies varied from 100 to 17 colonies. For surface water, the colony count showed the dominance of enterococci (14 colonies in 100 ml) compared to the other germs studied. For the water taken from 30 meters deep, the count revealed the appearance of 54 CFU of total coliforms in 100ml. The other germs showed either a total absence or estimated numbers of 13 CFU for staphylococci and 4 CFU for enterococci.
Bacteriological parameters of the fish
After incubation of the inoculum prepared on PCA, the decrease in the load as well as its absence in the other dilutions was confirmed by the work of
Josephson and Lindsay (1986) had confirmed that the flesh of the fish freshly sin was sterile, cells of the reticuloendothelial system were responsible for the phagocytosis of bacteria.
Ringo (1993) proved that at pH 3.5 to 4.5 in the stomach, the bacterial population level was estimated to be 104 up to 105 in one gram of faecal matter.
Muroga et al., (1987) showed that the bacterial load in the digestive tract was higher than that of the surrounding water, which indicated the presence of an ecological niche favorable to these bacteria. The microbial load of the Barbel was lower than that of the Bighead carp. According to the work of
Le Nguyen et al., (2008), water temperature influenced the predominance of a particular bacterial species.
Pelletier (2009) showed that the turbidity of the fluid could be modified following changes in its physical, chemical and microbiological properties. According to the
Brussels Institute for Environmental Management (2005) the high content of dissolved oxygen in water was due to the high photosynthetic activity in the medium.
Characterization of the purified strains
The macroscopic observation of the colonies (Fig 6) showed us a wide variety of strains present in the second sample of fish than those observed in the Barbel. These results corroborate with those found by
Shewan (1971). He showed that the diversity of fish species played a role in the diversity as well as the number of flora found: they differed from species to species. However, we observed a difference in the number of strains at the level of the superficial part of the fish compared to its intestinal part and the same with the pulpit, a number of 16 strains on the surface and 11 strains at the level of the intestine for the two fish taken: Barbel and Bighead carp. While a strain was isolated in Barbel. According to the research of
Valle (1996), the bacterial leads as well as the nature of the flora of the different organs are variable. The results of the Gram stain (Fig 7) were in agreement with
Liston (1980) who observed a high proportion of Gram positive bacteria in the flora of freshwater fish. In the intestinal part of the Barbel, the strains isolated were of Gram negative presenting the form of shell and bacilli. The proportion of facultative or strict anaerobes was higher than for surface and gill flora (
Valle 1996). A single strain of Gram negative bacillary form was isolated from the pulpit. An absence of spores for all the strains isolated was observed. Plating on Chromagar orientation medium of the isolated strains for the two fish samples had revealed.
From reading the galleries in the appropriate table (Table 2) (
Biomerieux 2002), the following species were obtained:
- Dam water
Staphylococcus sp; Serratia odorifera, Serratia ficaria; Vibrio fluviatis; Pseudomomas flurenscens; Pseudomomas putida, Pseudomonas luteola; E. coli; Stenotrophomonas maltophilia; Chrysobacterium meningosepctium.
-From the surface of fish
Staphylococcus sp; Streptococcus sp; Pseudomomas flurenscens, Pseudomomas putida, Pseudomonas luteola; Serratia odorifera, Serratia ficaria; Stenotrophomonas maltophilia; Lactobacillus sp;
Chrysobacterium meningosepctium; Stenotrophomonas maltophilia.
- Of the intestine of the analyzed fish
Staphylococcus sp; Streptococcus sp; Pseudomomas flurenscens, Pseudomomas putida, Pseudomonas luteola; Serratia odorifera, Serratia ficaria; Salmonella sp; Citrobacter broakii; Proteus mirabilis; Chrysobacterium meningosepctium; Lactobacillus sp.
The two genera of
Pseudomonans and
Serratia presented a greater variety of species than the other genera. These results were in agreement with the work of
Diabate et al., (2019) for the sample of fresh seawater fish. The presence of lactic acid bacteria during the analyzes of our samples were similar to those of
Hagi et al., (2004) who demonstrated the presence of lactic acid bacteria species
Lc. lactis and
Lc. raffinolactis found as dominant species of the intestinal flora of freshwater carp.