Exploration Of The Role On Quorum Sensing Gene LuxS In Cronobacter Malonaticus Under Environmental Stresses

Cronoabcter malonaticus is one of the types of human and animal intestinal parasitic gram-negative bacteria with flagellum,motility and facultative anaerobic activity.The pathogen contributes to neonatal meningitis,bacteremia and necrotizing enterocolitis with high mortality through powdered infant formula,which has attracted wide attention from all over the world.At present,C.malonaticus has a wide distribution in the natural environment,and there are few reports about regulatory mechanisms in stress.In this study,we used C.malonaticus wild-type(WT)strain and mutant ?LuxS as the research objects to carry out experiments of bacteria,biofilm and protein under various stresses.By the means of contrast,study is carried though survival rate,inhibition rate,motility,biofilm formation ability,changes in surface structure of biofilm,morphology changes of cell,differentially expressed proteins and other indicators of the two strains under stress to explore the role of quorum sensing gene LuxS in C.malonaticus.The results showed that the resistance to oxidative,osmotic and acid stresses of WT was significantly higher than the mutant ?LuxS.51 differential proteins such as catalase-peroxidase,superoxide dismutase,DNA protective protein,lactate dehydrogenase and Fe-S cluster assembly protein were up-regulated in WT under oxidative stress.These proteins are involved in 13 kinds of biological processes including catabolism,stress response,and biosynthesis.The two strains have significant differences in the expression levels of 68 proteins in S-ribosyl homocysteine lyase,TetR family transcriptional regulator,ribosomal protein,ABC transporter and Fe-S cluster assembly transcriptional regulator under osmotic stress.The differential proteins play important roles in transport,biosynthesis,small molecule metabolism and other biological processes.This study provides new insights in the stress mechanism of C.malonaticus,and adds an important basis for preventing the biofilm damage and the mechanism of action of LuxS in pathogenic bacteria.