An assessment of environmental factors influencing acid tolerance and sensitivity in Escherichia coli, Salmonella spp. and other enterobacteria.

Environmental factors such as temperature, pH and nutrient level affect enterobacterial acid sensitivity, as do the presence of phosphate and Na+ and the extent of aeration. The mechanisms governing these effects are partially understood and the involvement of phoE, fur and atp in acid tolerance, of phoE, envZ, tonB, (p)ppGpp and cAMP in salt-induced acid sensitivity and of rpoS in stationary-phase acid tolerance are of particular interest. It should be noted that surface attachment enhances acid resistance.