title: Acid resistance in Escherichia coli.
abstract: To colonize and cause disease, enteric pathogens must overcome environmental challenges that include acid stress in the host's stomach as well as short-chain fatty acid stress in the intestine of the host and reservoir. Three known inducible systems have evolved for stationary phase acid resistance in E. coli. These systems each provide a different level of protection with different requirements and induction conditions. Acid resistance system 1 (AR1) is acid induced in stationary phase, requires the presence of RpoS, and provides the least level of protection at pH 2.5. Acid resistance system 2 (AR2) is glutamate dependent and stationary phase induced, requires the presence of glutamate decarboxylase and a putative glutamate:GABA antiporter, and provides the highest level of protection. Acid resistance system 3 (AR3) is arginine dependent and acid induced under anaerobic conditions, requires the presence of arginine decarboxylase (AdiA), and provides only a modest level of protection. These three systems along with log phase acid tolerance protect cells from the acid stresses in both the reservoir and host, which can range from pH 2 to 4.5. They also protect against acid stress involved in food processing and facilitate the low infectious dose characteristic of E. coli, significantly contributing to the pathogenesis of this organism.
authors.affiliation: Department of Microbiology and Immunology, College of Medicine, University of South Alabama Mobile, Alabama 36688, USA.
authors.forename: Hope T
authors.initials: HT
authors.lastname: Richard
authors.forename: John W
authors.initials: JW
authors.lastname: Foster
mesh_terms: D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D004927:Escherichia coli Infections / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology; D006863:Hydrogen-Ion Concentration
chemical_list: D029968:Escherichia coli Proteins