Bifidobacterium spp. influences the production of autoinducer-2 and biofilm formation by Escherichia coli O157:H7

Anaerobe. 2012 Oct;18(5):539-45. doi: 10.1016/j.anaerobe.2012.08.006. Epub 2012 Aug 28.


The effect of Bifidobacterium spp. on the production of quorum-sensing (QS) signals and biofilm formation by enterohemorrhagic Escherichia coli (EHEC) O157:H7 was investigated. In an AI-2 bioassay, cell extracts of Bifidobacterium longum ATCC 15707 resulted in a 98-fold reduction in AI-2 activity in EHEC O157:H7 as well as in the Vibrio harveyi reporter strain, even though they did not inhibit the growth of EHEC O157:H7. In addition, they resulted in a 36% reduction in biofilm formation by the organism. Consistently, the virulence of EHEC O157:H7 was significantly attenuated by the presence of cell extracts of B. longum ATCC 15707 in the Caenorhabditis elegans nematode in vivo model. By a proteome analysis using two dimensional electrophoresis (2-DE), we determined that seven proteins including formation of iron-sulfur protein (NifU), thiol:disulfide interchange protein (DsbA), and flagellar P-ring protein (FlgI) were differentially regulated in the EHEC O157:H7 when supplemented with cell extracts of B. longum ATCC 15707. Taken together, these findings propose a novel function of a dairy adjunct in repressing the virulence of EHEC O157:H7.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Anti-Bacterial Agents / isolation & purification
  • Anti-Bacterial Agents / pharmacology*
  • Bifidobacterium / chemistry*
  • Biofilms / growth & development*
  • Caenorhabditis elegans / microbiology
  • Disease Models, Animal
  • Escherichia coli Infections / microbiology
  • Escherichia coli O157 / chemistry
  • Escherichia coli O157 / drug effects*
  • Escherichia coli O157 / pathogenicity
  • Escherichia coli O157 / physiology*
  • Escherichia coli Proteins / analysis
  • Homoserine / analogs & derivatives*
  • Homoserine / metabolism
  • Humans
  • Infant
  • Lactones / metabolism*
  • Microbial Interactions*
  • Proteome / analysis
  • Survival Analysis
  • Vibrio / growth & development
  • Vibrio / metabolism
  • Vibrio / physiology


  • Anti-Bacterial Agents
  • Escherichia coli Proteins
  • Lactones
  • N-octanoylhomoserine lactone
  • Proteome
  • Homoserine