Role of LuxR‐type regulators in fish pathogenic <i>Aeromonas hydrophila</i>

Abstract

Abstract LuxR‐type transcriptional factors are essential in many bacterial physiological processes. However, there have been no reports on their roles in Aeromonas hydrophila . In this study, six stable silent strains were constructed using shRNA. Significant decreases in the expression levels of luxR 05 , luxR 08 , luxR 19 , luxR 11 , luxR 164 and luxR 165 were shown in their respective strains by qRT‐PCR. The luxR 05 ‐RNAi and luxR 164 ‐RNAi exhibit the most significant changes in sensitivity to kanamycin and gentamicin. The luxR 05 ‐RNAi showed minimum biofilm formation and the least motility, while luxR 164 ‐RNAi showed minimum biofilm formation, adhesion, growth and extracellular protease activity compared to the wild‐type strain. In summary, the results of this paper suggest that all six luxR genes are involved in multiple physiological processes in A. hydrophila and that the roles of luxR 05 and luxR 164 are highly significant. The sensitivity of luxR 05 ‐RNAi and luxR 164 ‐RNAi to drugs may be closely related to biofilm formation. The luxR 05 may play an important role in the pathogenicity of A. hydrophila by regulating the movement, adhesion and biofilm formation of bacteria, whereas luxR 164 may be involved in similar functions by regulating bacterial adhesion, extracellular enzyme activity and growth. These results help further our understanding of the drug resistance and pathogenesis of A. hydrophila .