NUTRITION AND METABOLISM OF MARINE BACTERIA

Abstract

Takacs, Frank P. (McGill University, Montreal, Quebec, Canada), Tibor I. Matula, and Robert A. MacLeod . Nutrition and metabolism of marine bacteria. XIII. Intracellular concentrations of sodium and potassium ions in a marine pseudomonad. J. Bacteriol. 87: 510–518. 1964.—Washed cells of a marine pseudomonad were suspended in buffered salt solutions containing, in addition to MgSO 4 , NaCl and KCl at various concentrations. The cells were centrifuged from the medium and analyzed for Na + and K + . Inulin and C 14 -carboxypolyglucose were employed to estimate the volume of extracellular fluid associated with the packed cells. Intracellular Na + and K + concentrations were determined by correcting for the amount of Na + and K + in the extracellular fluid. At all levels of Na + in the suspending medium (0 to 1 m ), the intracellular and extracellular Na + concentrations within the limits of experimental error were the same. The intracellular K + concentrations were approximately double the extracellular concentrations at the two levels of K + tested (0.01 and 0.15 m ) and were not influenced by the amount of Na + present. Intracellular and extracellular Cl − concentrations were the same at the one level of Cl − examined. The intracellular fluid volume varied with the NaCl or KCl concentration of the suspending medium, being greatest in the absence of added salts, decreasing to a minimum at 0.3 m salt, and then increasing slightly at higher salt concentrations. Most of the intracellular Na + could be removed by washing with solutions of MgSO 4 or sucrose, but a small amount [10 to 15 μmoles/g (dry weight)] remained bound to the cells.