Gut Microbiota Dysbiosis Drives Lethal Bacterial Enteritis in Sturgeons: Insights From Ex Vivo Cultivation and Metagenomic Investigations.

The Chinese sturgeon (Acipenser sinensis) and Yangtze sturgeon (A. dabryanus) are critically endangered flagship species. To investigate the intestinal microbial changes associated with bacterial enteritis in captive populations, we integrated bacterial isolation with metagenomic sequencing to characterize both healthy and maladjusted gut microbiomes. Healthy sturgeons exhibited a stable microbiota dominated by the beneficial Cetobacterium. In contrast, enteritis was consistently associated with severe dysbiosis, characterized by the depletion of these commensals and the massive expansion of opportunistic pathogens, notably Aeromonas and Citrobacter. Culture-based analyses identified A. veronii, C. freundii and Plesiomonas shigelloides as the dominant cultivable bacteria from diseased individuals; these isolates harboured diverse virulence traits and were multidrug-resistant. Crucially, both sturgeon species showed highly similar microbial responses and pathogenic profiles during enteritis. These findings indicate that sturgeon enteritis is closely correlated with a dysbiosis-driven syndrome. Establishing the healthy baseline provides a critical theoretical foundation for screening autochthonous probiotics and developing targeted pathogen control strategies. Furthermore, the striking cross-species commonality validates the Yangtze sturgeon as a viable surrogate model for advancing disease management and conservation in the difficult-to-breed Chinese sturgeon.