AI-2-like acttivity mediated E. coli O157:H7 survival and virulence gene expression in the presence of ground beef extracts

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Title: AI-2-like acttivity mediated E. coli O157:H7 survival and virulence gene expression in the presence of ground beef extracts
Author: Soni, Kamleshkumar Arvindkumar
Abstract: Cell -to -cell communication , termed quorum sensing , mediated by AI -2 like activity , has been reported to regulate the expression of a variety of genes in E . coli O157 :H7 . A previous study in our laboratory has shown that foods can contain compounds that can interfere with AI -2 signaling . The underlying hypothesis of our studies is that the autoinducer molecules such as AI -2 are involved in the virulence and survival of enteric bacterial pathogens on food and food ingredients . The influence of AI -2 like activity on the survival and expression of virulence genes (hha and yadK ) in E .coli O157 :H7 was studied when the organism was stored in different types of ground beef extracts such as : cooked , uncooked , and autoclaved . The survival was observed at refrigeration temperature , while change in gene expression was studied using real -time PCR . Higher survival was observed in the cell exposed to cell free supernatant (CFS ) containing AI -2 like molecules , compared to the one which was exposed to heat degraded AI -2 like molecules . The survival of cells was higher when exposed to cooked ground beef extracts compared to uncooked and autoclaved ground beef extracts . Similarly , higher gene expressions of both hha and yadK genes were observed in cells that were exposed to cooked beef extract samples as compared to samples that wereuncooked or autoclaved . About a 2 fold higher gene expression for both hha and yadK gene was observed when cells were subjected to cooked ground beef extracts in the presence of AI -2 like molecules compared to the ones exposed to uncooked ground beef extracts in the presence of AI -2 like molecules . Likewise , 3 -fold higher gene expression was observed for cells exposed to cooked ground beef extracts compare to autoclaved ground beef extracts in the presence of AI -2 like molecules . The results suggest that the survival and virulence of enteric bacterial pathogens such as E .coli O157 :H7 can be influenced by the interaction of food components and autoinducers such as AI -2 , that are involved in bacterial cell communications .
URI: http : / /hdl .handle .net /1969 .1 /3967
Date: 2006-08-16

Citation

AI-2-like acttivity mediated E. coli O157:H7 survival and virulence gene expression in the presence of ground beef extracts. Available electronically from http : / /hdl .handle .net /1969 .1 /3967 .

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