Study On The Fuctions Of Genes Related To Desiccation Tolerance In Cronobater Sakazakii

Cronobacter sakazakii is a non-spore-forming,peritrichously flagellated,facultatively anaerobic food-borne pathogen associated with severe neonatal infection and high mortality.The bacterium can also cause gastroenteritis,sepsis,urinary tract infections,and wound infections in adults.C.sakazakii has some stress survival factors that enable it to survive various adverse environmental conditions,the most prominent of which is desiccation stress.However,the research on the mechanism related to desiccation resistance of the bacteria is not clear at present,and more in-depth research is urgently required as a theoretical support to prevent and control the hazard caused by this pathogen.In our previous studies,some genes were proved to be related to desiccation tolerance.In this study,two genes,ESA-03422 and ESA-00281,were selected to explore their roles in desiccation tolerance and other related characteristics.In this study,two gene knockout strains of ESA-03422 and ESA-00281(ΔESA-03422,ΔESA-00281)were constructed by homologous recombination,and the corresponding complementing strains were constructed using the p ACYC184 plasmid to explore the role of these two genes in the desiccation tolerance of C.sakazakii ATCC BAA-894.The results showed that the ESA-03422 gene had a positive regulatory effect on the desiccation tolerance of C.sakazakii.High-throughput sequencing technology was used to further compare the changes of gene expression in the wild strain and the deletion strain after desiccation challenge.Transcriptome analysis showed that 114 genes were up-regulated and 22 genes were down-regulated after the ESA-03422 gene was knocked out.Some flagellar genes and chemotaxis-related factor genes were up-regulated,and some amino acid metabolism genes were significantly up-regulated.These results indicated that this gene may regulate the desiccation tolerance of the strain by increasing cell movement,energy consumption and transporting osmotic regulators.In addition,it was also confirmed that this gene played a negative regulatory role in the motility,surface hydrophobicity and biofilm formation of C.sakazakii,but there had no significant effect on the ability of the strain to adhere to and infect host epithelial cells.The deletion of the ESA-00281 gene resulted in a significant decrease in the desiccation tolerance of the strain,indicating that the gene plays a positive role in the desiccation tolerance mechanism of C.sakazakii.In addition,this gene also plays a positive role in cell adhesion,surface hydrophobicity and biofilm formation of C.sakazakii,indicating that this gene might regulate the desiccation resistance of the strain by regulating cell adhesion,surface hydrophobicity and biofilm formation.Based on the systematic study of the functions of ESA-03422 and ESA-00281 genes,this study laid a good foundation for understanding the mechanism underlying desiccation resistance and hazard of C.sakazakii,and provided a reference for the prevention and treatment of this pathogen.