Dysbiosis of the gut microbiota in white-gill diseased large yellow croaker (Larimichthys crocea)

White-gill disease, a newly emerged infectious disease with high mortality, has caused great losses to large yellow croaker (LYC) Larimichthys crocea cage aquaculture industry in the southeastern coastal of China. However, the etiology and pathogenic mechanism of white-gill disease are still unclear, and the research on the intestinal microbiota of LYC associated with white-gill disease is not yet available. In this study, we used 16S rRNA gene amplicon sequencing to investigate the diversity, composition, stability and assembly processes of intestinal microbiota in healthy and diseased LYCs.The composition of intestinal microbiota in LYC is mainly affected by different growth stages (juvenile/adult) and aquaculture sites. Health status (healthy/white-gill diseased) is also an important factor in the variation of intestinal microbiota composition in LYC. The key differential taxa in the intestinal microbiota between white-gill diseased and healthy LYCs were largely consistent across aquaculture sites and growth stages. The pathogen Photobacterium damselae subsp. damselae proliferated massively in the intestines of white-gill diseased LYCs, and the common probiotic Bacillus appeared in higher relative abundance in the intestine of healthy LYC. In addition, the diversity and stability of intestinal microbiota in white-gill diseased LYCs were reduced, and the stochastic processes were enhanced in community assembly.Our study elucidate the close association between gut microbiota and white-gill disease from a microbial ecological perspective, providing a scientific basis for the development of microbiota-informed diagnostic and preventive strategies.