Extrusion of Sodium Ions Energized by Respiration and Glycolysis in Escherichia Coli

Extrusion of sodium ion from cells of Escherichia coli was measured using an Na+ electrode. When oxygen was supplied to an anaerobic cell suspension, extrusion of Na+ was observed. The addition of glucose under anaerobic conditions also caused Na+ efflux. The extrusion of Na+ energized by respiration and glycolysis was completely inhibited by a proton conductor, carbonyl cyanide m-chlorophenylhydrazone. These observations are consistent with the view that Na+ transport occurs secondarily to H+ circulation. Interestgly, induction of the melibiose transport system, which is coupled to Na+, greatly enhanced Na+ transport activity.