[Relation between H2 production and energy-dependent metabolism of H+ and K+ ions in E.coli]

Anaerobically grown E. coli escape H2 into the medium during the operation of H(+)-K(+)-pump exchanging 2H+ from a cell for one K+ of the medium. Anaerobic cells grown in the nitrate medium as well as the aerobically grown bacteria possessed neither 2H+/K+ exchange system, nor the ability for H2 production. Introduction of N,N'-dicyclohexylcarbodiimide into the medium, the removal of external K+ or the decrease of external osmotic pressure blocked both the functioning of H(+)-K(+)-pump and H2 production. The substitution of glucose by lactate reduced the activity of bacteria without change in pump operation and H2 production. It is assumed that formate-hydrogen lease and H(+)-K(+)-pump are working in collaboration.