Study of the gut microbial diversity of Mytilus coruscus with different growth rates.

To examine intestinal microbiota-growth rate relationships in Mytilus coruscus, we analyzed genetically similar individuals under uniform aquaculture conditions using 16S rRNA sequencing, comparing fast-growing (L) and slow-growing (S) groups. Results demonstrated that Proteobacteria and Bacteroidota were the dominant phyla in the intestine of M. coruscus, and Pseudoalteromonas and Vibrio were the dominant genera. The relative abundances of Proteobacteria (84.30%) and Pseudoalteromonas (44.64%) in group L were significantly higher than those in group S (69.50% and 15.41% respectively), while the relative abundances of Bacteroidota (9.49%) and Tenacibaculum (2.21%) in group L were significantly lower than those in group S (19.42% and 4.54% respectively) (p < 0.05). In terms of diversity analysis, the microbial α diversity (Shannon and Simpson indices) in group L was significantly lower than that in group S. Beta diversity analysis (PCoA and PERMANOVA) showed that there were significant differences in the intestinal microbiota structure between group L and group S. Pearson correlation analysis further found that the relative abundance of Amphritea was significantly positively (r = 0.78-0.81, p < 0.05) correlated with the growth rate of M. coruscus, while Tenacibaculum was significantly negatively (r = -0.72-0.73, p < 0.05) correlated. In addition, functional prediction via PICRUSt indicates Amphritea may promote growth by enhancing host nutrient metabolism, while Tenacibaculum enrichment might hinder host development through resource competition or metabolic interference. This study demonstrates the association between M. coruscus growth rate and gut microbiota, provides a basis for promoting its growth by regulating the intestinal microbiota, and holds significant reference value for efficient aquaculture production and health management.