GLYCEROL ELICITS ENERGY TAXIS OF ESCHERICHIA-COLI AND SALMONELLA-TYPHIMURIUM

Escherichia coli and Salmonella typhimurium shots positive chemotaxis to glycerol, a chemical previously reported to be a repellent for E, c oli, The threshold of the attractant response in both species; was 10( -6) M glycerol, Glycerol chemotaxis was energy dependent and coinciden t with an increase in membrane potential, Metabolism of glycerol was r equired for chemotaxis, and when lactate was present to maintain energ y product-ion in the absence of glycerol, the increases in membrane po tential and chemotactic response upon addition of glycerol were abolis hed. Methylation of a chemotaxis receptor was not required for positiv e glycerol chemotaxis in E, coli or S, typhimurium but is involved in the negative chemotaxis of E. coli to high concentrations of glycerol, We propose that positive chemotaxis to glycerol in E. coli and S. typ himurium is an example of energy taxis mediated via a signal transduct ion pathway that responds to changes in the cellular energy level.