The effect of isolated bacteria from the intestinal duct of Beluga (Huso huso) fingerling on biochemical compounds of body extract, excretion of metabolic nitrogen and survival of Common Carp (Cyprinus carpio) larvae against environmental stresses

In a nutritional experiment, Bacillus subtilis, Bacillus lichenifirmis and yeast of Saccharomyces cerevisiae isolated from the intestine of Beluga (Huso huso) in suspended blend at three different concentrations (1.5×106, 3×106 and 4.5×106 CFU/g) and added to basal diet and considered as experimental treatments. The common carp (Cyprinus carpio) larvae were fed the experimental diet for a period of 45 days. At the end of the feeding period, larvae were exposed to various environmental stresses challenges containing: high level of ammonia (5 mg/L), high thermal pressure (40Cᵒ), low Acid (pH=2) and high Alkaline (pH=12) conditions. Furthermore, Biochemical parameters were measured after preparing the larval body extract through the routine method. The results showed that growth indices increased significantly in experimental treatments compared to control group (p <0.05). The highest survival rate of larvae was recorded in T3 treatment against environmental stresses (p < 0.05). The highest Na+ and K+ ions in larval body extract was measured in T3 treatment (p <0.05). The highest glucose level was measured in T2 treatment (p <0.05). Cortisol level in T3 treatment was significantly lower than other experimental treatments (p <0.05). The results of this study indicated that the simultaneous use of Bacillus and yeast probiotics in diet of common carp larvae, isolated from the gastrointestinal tract of Beluga, had positive and significant effects on improving the growth parameters, biochemical compounds of body extract, survival rate and resistance against environmental stresses, especially, at the level of 4.5 10 106 CFU/g.