The amount of probiotic bacteria <i>Bacillus subtilis</i> ssp. <i>spizizenii</i> supplemented in the feed influences the survival and severity of damage to the shrimp hepatopancreas during an infective process

ABSTRACT Objective The objective of this study was to evaluate the effect of Bacillus subtilis ssp. spizizenii supplementation on survival and hepatopancreas damage in Pacific white shrimp Penaeus vannamei during infection with Vibrio alginolyticus. Methods The experimental design was completely randomized, with four treatments (concentrations) in triplicate, D0 (control, without B. subtilis addition), D8 (1 × 108 CFU/kg of feed), D9 (1 × 109 CFU/kg of feed), and D10 (1 × 1010 CFU/kg of feed). The shrimp were subjected to a 4-week dietary regimen, followed by exposure to an infective challenge with a pathogenic strain of V. alginolyticus (1 × 105 CFU/mL). Throughout this period, water quality and productive responses were measured. Results Productive parameters exhibited a positive trend corresponding to the quantity of bacteria that was incorporated into the feed. Upon completion of the bacterial challenge (120 h), treatment D0 presented the lowest survival rate (61.3%) and D10 exhibited the highest (93%). During the bacterial challenge, the abundance of V. alginolyticus in the shrimp hepatopancreas showed a negative correlation with the level of B. subtilis supplementation in the diet (r = −0.96, P &amp;lt; 0.05). The histopathological analysis uncovered the most severe damage in D0, whereas treatments D8–D9 displayed minor lesions, and D10 had minimal damage. Conclusions Beyond enhancing the productive response, the dietary supplementation of B. subtilis ssp. spizizenii exhibited a significant correlation with the diminished presence of V. alginolyticus in the shrimp hepatopancreas, alleviated tissue damage, and contributed to increased survival rates. This bacterium can be considered as an alternative supplement in shrimp farming.