The Response Mechanism of Klebsiella pneumoniae to H₂O₂ Oxidative Stress

Objective:This study aimed at revealing the effect of host intestinal oxidative condition on Klebsiella pneumoniae and its mechanism of response to oxidative stress.Method:In vitro intestinal oxidative conditions,Klebsiella pneumoniae was inoculated in liquid medium containing different concentration of H₂O₂ for oxidative stress treatment,the growth curve of bacteria was measured,and the key virulence factors of bacteria--capsule and biofilm were examined. Furthermore,qRT-PCR quantitative analysis was used to analyze the differences in the expression of genes related to the phenotype of the capsule and biofilm. Results:The results showed that under condition of H₂O₂ oxidative stress,when it was in a lower concentration range(<1.56 mmol/L),the early growth stage of Klebsiella pneumoniae was inhibited,and it gradually adapted to stress in the middle and late stages,and the growth was not significantly affected. The production of Klebsiella pneumoniae capsule was significantly reduced with a dose-dependent effect;while under a certain concentration range of oxidative factors,the amount of biofilm formation increased. And molecular testing showed that the expression level of the capsular structure gene magA was significantly down-regulated,and the biofilm-related gene YbaJ was significantly up-regulated. Conclusions:Taken the results together,Klebsiella pneumoniae could up-regulate the expression of gene YbaJ to promote the formation of virulence factor biofilm in response to oxidative factor stress,which provided new ideas for the study of the interaction between Klebsiella pneumoniae and host intestinal factors and the pathogenic mechanism.