Aeromonas hydrophila is a common opportunistic pathogen in aquaculture, which readily infects sturgeon under stress conditions. This study investigated the prophylactic efficacy of Lactococcus petauri strain JLlg08PX against A. hydrophila in hybrid sturgeon (Acipenser baerii × Acipenser schrencki). In vitro experiments revealed that the cell-free supernatant of L. petauri significantly inhibited A. hydrophila growth by disrupting bacterial cell integrity, leading to DNA and lactate dehydrogenase (LDH) leakage. In a 21-day feeding trial, hybrid sturgeon fed L. petauri exhibited significantly reduced mortality after A. hydrophila challenge, alongside decreased pathogen loads in the liver and head kidney. Concurrently, serum levels of nitric oxide (NO) and lysozyme were elevated. Histopathological analysis demonstrated that the L. petauri supplemented group alleviated hepatic damage, maintained intestinal epithelial integrity, reduced inflammatory responses and tissue lesions. These findings indicated that L. petauri JLlg08PX reduced A. hydrophila infection risk in hybrid sturgeon through dual mechanisms, direct antagonism of the pathogen and enhancement of innate immunity. This study provides a novel strategy for eco-friendly disease control in aquaculture.
 

Lactococcus petauri；Aeromonas hydrophila；Antagonistic effect；Anti-infection；Sturgeon