[Systems of H+ K+ ion exchange in E. coli]

Membrane potentials in bacteria E. coli have been estimated by means of electrodes for determination of activity of tetraphenilphosphonium ions in the medium. The strain E. coli K12 (lambda), TK 509, AN 120 and AN 382 indicate the membrane potential (delta psi) of -125 mV in the salt solution without glucose (2 mM KCl, tris-phosphate buffer, pH 7.5). The delta psi of the first three strains include that N,N1--dicyclohexylcarbodiimide (DCCD)--sensitive part (20--25 mV) that has not been detected in the strain AN 382 (F0 is resistant to DCCD). This component of delta psi eliminated by (alpha K+)0 equal to 30 mM or pH 5.0, is assumed to be produced by activity of the channel F0 deprived of its enzyme F1. Addition of glucose in the medium leads to the short-lasting (2--5 min) increase in the delta psi from 125 to 145 mV in E. coli K12 (lambda). This energy-dependent extra potential is actuated only through increasing external osmolarity and does not occur after decreasing that or application of DCCD as well. The extra delta psi was not recognized in the strains TK 509 and AN 120. The results confirm the hypothesis of the energy-dependent potassium accumulation in glycolysing bacteria being not in need of ATP and delta muH+ but requiring in operation of F1 . F0.