ENERGY OF MAINTENANCE IN ESCHERICHIA COLI

Abstract

Relatively dense populations of Escherichia coli B in log phase were used to detect utilization of exogenous glucose for maintenance without growth. Turbidity at 400 mu was used as the measure of growth since it should reflect changes in either cell number or size. A threshold level of glucose was observed below which turbidity did not change during short-time experiments. Repeated additions of glucose during prolonged incubation at 37 C either increased the turbidity slowly or maintained it depending on the amount of glucose. Plate counts to follow viability showed slow decreases for 10 days while the unfed controls lost viability quite rapidly. From these results it was concluded that E. coli specifically utilized exogenous glucose for maintenance without growth. The conflict of this opinion with that of earlier workers is discussed and some implications suggested.