An endogenous synthetic bacterial community mitigates nitrite toxicity in shrimps

Intensive shrimp aquaculture has led to the excessive accumulation of nitrite, resulting in shrimp mortality and posing a widespread challenge to aquaculture systems. In this study, we analyzed the gut bacterial communities of shrimp that either survived or died after exposure to a semi-lethal concentration of nitrite for 72 h. We isolated 17 bacterial strains to construct a potential endogenous probiotic consortium, which significantly enhanced shrimp survival under acute nitrite stress. Colonization experiments revealed that three of these strains successfully colonized the shrimp gut. Strain LvS229, belonging to the genus Tenacibaculum, emerged as a key member of the consortium, exhibiting a distinct colonization advantage. Pre-treatment with LvS229 conferred sustained protection, significantly enhancing shrimp survival rates under nitrite challenge and highlighting its pivotal role in EnPB-mediated tolerance. Mechanistically, genomic and metabolism assays revealed its possession of functional nitrite-reductase genes, enabling the reduction of ambient nitrite. By alleviating oxidative stress and boosting immune and antioxidant enzyme activities, LvS229 transplantation effectively promoted host resilience. Collectively, these findings provide novel insights and a promising probiotic strategy for mitigating environmental stress in shrimp aquaculture.