Energy requirement for maintenance of the transmembrane potassium gradient in Klebsiella aerogenes NCTC 418: A continuous culture study

Abstract

With a glucose-limited culture of Klebsiella aerogenes, growing at a fixed dilution rate (0.4 h^-1), the specific respiration rate varied progressively as a function of the transmembrane K⁺ gradient. The latter was varied by changing the input K⁺ concentration and, under these conditions, the specific respiration rate was linearly related to the electrochemical potential of the K⁺ gradient. Increasing or decreasing the transmembrane K⁺ gradient in putatively potassium-limited cultures elicited marked changes in respiration rate consistent with the conclusion that the exceptionally high respiration rates expressed by fully glucose-sufficient potassium-limited cultures (i.e., values in excess of 25 mmol O₂/g dry weight organisms · h, at D=0.4 h^-1) are necessary to scavenge traces of K⁺ from the environment and hence maintain an exceptionally high transmembrane K⁺ gradient.