The Primary Physiological Roles of Autoinducer 2 in <i>Escherichia coli</i> Are Chemotaxis and Biofilm Formation

Abstract

Autoinducer 2 (AI-2) is a ubiquitous metabolite but, instead of acting as a “universal signal,” relatively few phenotypes have been associated with it, and many scientists believe AI-2 is often a metabolic byproduct rather than a signal. Here, the aim is to present evidence that AI-2 influences both biofilm formation and motility (swarming and chemotaxis), using Escherichia coli as the model system, to establish AI-2 as a true signal with an important physiological role in this bacterium. In addition, AI-2 signaling is compared to the other primary signal of E. coli, indole, and it is shown that they have opposite effects on biofilm formation and virulence.

Keywords

• AI-2
• chemotaxis
• aggregation
• biofilm
• motility
• <i>Escherichia coli</i>