Study On The TolC Gene Of Cronobacter SPP.Under The Stress Of Common Intestinal Bacteriostatic Agents

Cronobacter spp.is a foodborne pathogen mainly transmitted by the infant formula milk powder.The mortality rate of infected infants is as high as 40%-80%,accompanied by serious sequelae.Cronobacter spp.needs to face the complex intestinal environment of the low oxygen,short chain fatty acids,bile salts and the high osmotic pressure to survive in the intestinal tract.The tol C gene has been proved to be involved in bacteria's tolerance to bile salts,antibiotics,organic acids,disinfectants and other substances,as well as related to bacterial biofilm formation and virulence.However,the effect of tol C on the intestinal bacteriostatic agent stress of Cronobacter spp.has not been reported.This topic with Cronoabcter malonaticus wild strains and the mutant strains ?tol C as the research object,first observed the influence of the bacterial growth curve,the colony morphology and the outer membrane structure of the bacterial tol C gene mutation;and then the growth curve,relative growth rate,morphology,motility and biofilm formation ability of the two strains under the stress of common intestinal bacteriostatic agent bile salts were compared to explore the role of tol C;and also tested the effect of acr AB-tol C system on the bile salt efflux of Cronobacter spp..The results showed that the tol C gene mutation of C.malonaticus slightly increased the quantity of bacteria during the stable period,and significantly affect the colony morphology and the outer membrane structure of bacteria.The growth curve,relative growth rate,morphology,motility and biofilm formation ability and other indicators of the two strains under bile salts stress were significantly different.The acr AB-tol C system is an important system for cholestine efflux of C.malonaticus.The growth curve,relative growth rate,morphology and biofilm formation ability of the two strains under the stress of common intestinal bacteriostatic agent butyric acids were compared to explore the role of tol C.The results showed that the growth curve,relative growth rate,morphology and biofilm formation ability and other indicators of the two strains under butyric acids stress were significantly different.The growth curve,relative growth rate,morphology and biofilm formation ability of the two strains under the stress of the common intestinal bacteriostatic agent NO donor sodium nitroprusside were compared to explore the role of tol C.The results showed that the growth curve,relative growth rate,morphology and biofilm formation ability and other indicators of the two strains under the sodium nitroprusside stress were significantly different.The above experimental results suggest that tol C gene is closely related to the tolerance mechanism of C.malonaticus in common intestinal bacteriostatic agent stress.Experimental results of this study provide a new idea for the stress mechanism of common intestinal bacteriostatic agents of Cronobacter spp.and lays an important foundation for the prevention and control of the harm of Cronobacter spp..