X. Experim ents on the uptake of radioactive potassium, rubidium and phosphorus Alkali-metal ions in the metabolism of . la d is aerogenes

By the use as tracers of 42K, 86Rb and 32P it has been shown that in the metabolism of Bact. lactis aerogenes (а) the alkali-metal ion enters the cell during oxidation of the carbon substrate (glucose, succinic acid, acetic acid), whether or not a nitrogen source is provided, so that growth occurs; in either event the alkali-metal ion subsequently leaves the cell again; (б) if the pH is lowered the maximum uptake of the cation by the functioning cell is raised, although increased hydrion concentration first causes displacement of alkali-metal ions from resting cells; (c) in the early stages of growth, or of glucose oxidation without growth, the flow into the cell of alkali cations and of phosphate anions takes place in a parallel way.