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. Academic Article uri icon


  • 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 degrees 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.

published proceedings

  • J Food Sci

author list (cited authors)

  • Soni, K. A., Lu, L., Jesudhasan, P. R., Hume, M. E., & Pillai, S. D.

citation count

  • 29

complete list of authors

  • Soni, KA||Lu, L||Jesudhasan, PR||Hume, ME||Pillai, SD

publication date

  • April 2008