ATP synthesis driven by a potassium diffusion potential in Methanobacterium thermoautotrophicum is stimulated by sodium

ATP synthesis driven by a potassium diffusion potential was studied in cell suspensions of Methanobacterium thermoautotrophicum (Marburg). This transient increase in the intracellular ATP content was stimulated five-fold by the addition of sodium ions, from about 2 nmol ATP/min × mg cells (dry weight) at 0.07 mM Na+ to about 10 nmol ATP/min × mg cells at 25 mM Na+.