The role and mechanisms of rstA in the intracellular survival of fish pathogenic Aeromonas hydrophila.

In this study, RNAi technology was used to silence the gene rstA in Aeromonas hydrophila. The strain rstA-RNAi displayed significant decrease in intracellular survival compared with that of the wild-type strain B11. Transcriptome analysis explored that the expression of some important anti-stress protein genes was significantly upregulated in rstA-RNAi compared with the wild-type strain, while the expression of the genes related to iron acquisition and type VI secretion system was significantly downregulated. Further study found that under low pH and H 2 O 2 stress, the anti-stress protein genes were expressed at a low level in rstA-RNAi, the growth ability of rstA-RNAi was also significantly lower than that of wild-type strain. The results also displayed that with the fluctuation of iron concentration, the expression of some genes related to iron acquisition remained at a low level in rstA-RNAi, and the growth ability of rstA-RNAi was lower than that of the wild-type strain under the same culture conditions, indicating rstA can regulate iron acquisition and further affect the bacteria growth. The adhesion ability of rstA-RNAi to fish macrophages was reduced, suggesting rstA may be also affect the formation of type VI secretion system of A. hydrophila.