Abstract
To elucidate the interactions among fatty acid metabolism, immune status, and gut microbiota, both cultured and wild Coilia nasus from the Yangtze River were examined in China. The results demonstrated that wild C. nasus exhibited markedly higher lipid and docosahexaenoic acid (DHA) contents, a greater ratio of total ω-3 PUFAs to total ω-6 PUFAs, and more active antioxidant enzymes compared to cultured C. nasus. However, the shear force, water-holding capacity, and total n-6 PUFA content were lower in wild C. nasus. Transcriptome analysis revealed distinct gene expression patterns: wild C. nasus upregulated immune-related genes, while cultured C. nasus downregulated genes related to fatty acid metabolism. Significant differences were observed in alpha and beta diversity between cultured and wild groups. LEfSe analysis identified Clostridium_T, Escherichia, and Glutamicibacter as biomarkers for cultured C. nasus, while eight genera, including Pseudomonas_E and Sphingomonas_L, were predominant in wild C. nasus. Modular analysis identified five modules linked to immune functions and fatty acid metabolism. Clostridium_T, Sphingomonas_L, and Pseudomonas_E were dominant in the first two modules, with Pseudomonas_E and Clostridium_T as key regulators of fatty acid metabolism and immune processes. These differences, likely due to gut microbiota variations, provide insights for C. nasus nutritional studies.