Studies On The Funcyion And Effect Mechanism Of The Genes Related To Desiccation Tolerance Of Cronobacter Sakazakii

Cronobacter sakazakii(C.sakazakii)is a foodborne pathogen that can cause infection of newborns,the elderly and immunocompromised populations,with high infection rate and mortality.C.sakazakii is widely found in the environment and food,causing great harm to human beings,which has aroused widespread concern.Outstanding resistance to drying of this strain is an important cause of harm.However,the research on desiccation resistance mechanism of this strain is still not thorough enough.Therefore,on the basis of the previous research,this study systematically studied the function and mechanism of two genes related to desiccation tolerance of C.sakazakii.Flagellate hook-associated protein(FlgK)is a part of flagellate complex and may play an important role in desiccation tolerance of C.sakazakii.In this study,the flgK mutant strain(ΔflgK)was constructed using the homologous recombination method,and the complementary strain(cpflgK)was obtained.By comparing the characteristics of C.sakazakii ATCC BAA-894 wild-type(WT),ΔflgK and cpflgK,it was found that flgK gene had no significant effect on the growth and biofilm formation of C.sakazakii.However,the deletion of flgK gene resulted in the loss of motility,reduced adhesion ability and enhanced dehydration resistance of the strain.The gene expression of WT and ΔflgK strains after drying was compared by RNA-seq technology,and verified by q RT-PCR.The results showed that the expression levels of 54 genes were significantly up-regulated and 50 genes were significantly down-regulated.RNA-seq data further indicated that ΔflgK strains may up-regulate formate dehydrogenase,betaine synthesis and arginine deaminase pathways to resist dynamic proton imbalance caused by flagellum loss,and these pathways play important roles in environmental stress tolerance of C.sakazakii.ESA＿01393 gene encodes a hypothesized protein in C.sakazakii ATCC BAA-894.Compared with the protein sequence of yeb G gene(DNA damage-inducing protein)of Escherichia coli in NCBI,the identity of ESA＿01393 gene in C.sakazakii was 68%.In this study,the ESA＿01393 mutant strain(ΔESA＿01393)was constructed using the homologous recombination method,and the complementary strain(cp ESA＿01393)was obtained.By comparing the characteristics of C.sakazakii ATCC BAA-894 wild-type(WT),ΔESA＿01393 and cp ESA＿01393,it was found that ESA＿01393 gene had no significant effect on the growth,motility,and biofilm formation of C.sakazakii,and is involved in the process of desiccation resistance and DNA damage repair.Therefore,this study lays a foundation for further elucidating the function and mechanism of genes related to desiccation tolerance of C.sakazakii,and provides reference for effective control of this pathogen.