Sodium-dependent growth and respiration of a nonhalophilic bacterium, Pseudomonas stutzeri

Pseudomonas stutzeri (van Niel strain) requires Na+ for growth. Its growth rate was a sigmoidal function of Na+ concentration, being maximal and constant from 2 to 50 mM-Na+, and half maximal at about 0-5 mM-Na+. The relationship between cell concentration and Na+ concentration was non-linear; cell concentration increased abruptly when Na+ was greater than 0-3 mM. Accumulation of Na+ in the organism during growth was not detected. In the presence of K+, respiration was enhanced specifically by Na+. The respiration rate of the organism growing in the culture was a linear function of the growth rate when limited by the Na+ concentration, whereas the maximum rate induced by excess Na+ was independent of the growth rate.