Osmotic stress drastically inhibits active transport of carbohydrates by Escherichia coli

Abstract

In intact Escherichia coli cells, severe osmotic stress almost totally inhibited active transport of carbohydrate by all of the systems known to transport carbohydrates in E. coli: group translocation (glucose), binding-protein mediated transport (maltose), proton symport (lactose), and sodium cotransport (melibiose). Detailed study of glucose transport showed that this inhibition of transport was not secondary to the inhibition of growth by osmotic stress, but rather that the inhibition of transport of a source of carbon and energy was sufficient to cause the complete inhibition of growth observed during severe osmotic upshock. Transport and growth inhibition did not result from cell death; upshocked cells were viable and metabolically active.