The effect of N-acyl-homoserine lactones-mediated quorum sensing on intestinal colonization and damage by Aeromonas veronii

Aeromonas veronii can cause severe aquaculture-related diseases through the production of virulence factors, which are mediated by quorum sensing, but little is known about the impact of quorum-sensing systems on intestinal colonization by A. veronii. Therefore, in this study, an acyl-homoserine-lactones (AHLs) synthase gene (ahyI) mutant strain was constructed to investigate its intestinal colonization and damage on zebrafish intestine. The mutant strain reduced the production of biofilm and exogenous C4-HSL could increase its biofilm produc-tion. The intestinal colonization of mutant strain was significantly (P < 0.05) lower than that of wild strain and the addition of C4-HSL, but the intestinal colonization of the mutant strain was significantly (P < 0.05) increased in the ampicillin pretreated zebrafish with less colonization resistance, which indicated that AHLs-mediated quorum sensing can enhance defense against colonization resistance. Meanwhile, histopathological analysis and 16S rRNA gene sequencing confirmed that AHLs-mediated quorum sensing promotes the damage caused by A. veronii to intestinal structures and the disruption of the commensal bacterial community. Therefore, our study determined the effect of AHLs-mediated quorum sensing on intestinal colonization by A. veronii as well as its defense against colonization resistance, which provides a basis for further study on intestinal colonization by pathogens.