Isolation, characterization and application of probiotic Lactobacillus sakei from Larimichthys crocea intestine.

Currently, disease management is a major challenge for high-density aquaculture in China and a major factor limiting the healthy and sustainable development of our aquaculture industry. Research on fish-derived probiotics as safe feed additives is still relatively limited. In this study, we screened Larimichthys crocea for intestinal lactobacilli, obtained high adhesion strain Lactobacillus sakei YLD10, and further investigated its probiotic function and mechanism of resistance to Pseudomonas plecoglossicida infection. YLD10 significantly increased the growth rate and the digestive enzyme activities in the intestine, improved the antioxidant capacity and promoted the non-specific immunity of the L. crocea after 56 days. The L. crocea in the YLD10 group had longer intestinal villi and thicker intestinal wall, and reduced the abundance of Stenotrophomonas, Pseudomona and Acinetobacter. After gavage with P. plecoglossicida, YLD10 L. crocea had lower tissue burden, less tissue damage, and transcriptome analysis showed that excessive inflammatory response could be reduced by IL-17 pathway, which significantly improved the survival rate of L. crocea. The findings of the present study have enriched probiotic microorganisms in L. crocea aquaculture, and moreover have provided an innovative antimicrobial-free strategy with which to prevent and control bacterial disease in aquaculture.