Integrative Analysis of Gut Microbiota and Metabolome Reveals Health Benefits of Postbiotic Supplementation in Asian Seabass (Lates calcarifer)

This study evaluated the effects of dietary SYNSEA Premium postbiotics on growth, immunity, disease resistance, intestinal microbiota, and host metabolism in Asian seabass (Lates calcarifer). Fish were fed a control diet or diets supplemented with heat-killed Lactiplantibacillus plantarum LP28, L. plantarum LP1008, and Bacillus subtilis at 108 (LSP) or 109 (HSP) cells kg−1 diet for 56 days. Postbiotic supplementation did not significantly affect growth performance, feed efficiency, production, condition factor, or dorsal muscle composition, but significantly improved survival. Fish receiving postbiotics also exhibited higher survival following Vibrio alginolyticus and iridovirus challenges. These protective effects were accompanied by enhanced superoxide dismutase, phagocytic, and lysozyme activities and modulation of immune-related genes, including tgf-β1, tnf, ifn-γ1, c3, and mx. Exploratory microbiome and metabolome analyses, which were restricted to the control and LSP groups, identified differences in the relative abundance of specific intestinal microbial taxa and associations between microbial composition and host metabolic profiles. The LSP group showed lower relative abundances of potential pathogens such as Salmonella enterica, Lactococcus garvieae, and Staphylococcus warneri, although the overall microbial community structure did not differ significantly between groups. Metabolomic analysis of the LSP group further showed changes in D-glucose, pentose phosphate pathway intermediates, reduced glutathione, CoA, and 2-methylacetoacetyl-CoA relative to the control. Collectively, SYNSEA Premium improved survival, immune responses, and resistance to bacterial and viral infections without significantly affecting growth performance, while exploratory omics analysis of the LSP treatment identified associated microbial and metabolic changes.