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Influence of Autoinducer‐2 (AI‐2) and Beef Sample Extracts on E. coli O157:H7 Survival and Gene Expression of Virulence Genes yadK and hhA
Author(s) -
Soni K.A.,
Lu L.,
Jesudhasan P.R.,
Hume M.E.,
Pillai S.D.
Publication year - 2008
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2007.00654.x
Subject(s) - virulence , escherichia coli , gene , microbiology and biotechnology , biology , pathogen , autoinducer , mutant , gene expression , virulence factor , quorum sensing , biochemistry
Bacterial cell‐to‐cell communication is mediated by autoinducer (AI) molecules such as AI‐2 and has been reported to regulate gene expression in Escherichia coli O157:H7. We have previously shown that ground beef contains compounds that can inhibit sensing of AI‐2 like activity. The hypothesis of this study was that AI‐2 activity observed in conditioned medium (CM) will enhance E. coli O157:H7 survival and expression of virulence genes, whereas compounds inhibitory (such as those present in ground beef extracts) to AI‐2 activity will negate these effects. E. coli O157:H7 luxS mutant strain VS 94 (incapable of synthesizing AI‐2) was employed in these studies. The survival of this enteric bacterial pathogen as a function of AI‐2 activity and the presence of AI‐2 inhibitory compounds was studied at 4 °C. The number of survivors in the presence of AI‐2 was significantly higher compared to the absence of AI‐2, and the addition of ground beef extracts to conditioned medium negated the influence of AI‐2 activity. Autoinducer AI‐2 upregulated selected genes virulence genes ( yadK , and hha ), whereas the ground beef extract reversed the effect of AI‐2 on the expression of the selected genes.