EFFECTS OF SODIUM AND POTASSIUM CHLORIDE ON CERTAIN ENZYMES OF MICROCOCCUS HALODENITRIFICANS AND PSEUDOMONAS SALINARIA

Abstract

The isocitric, succinic, malic, and lactic dehydrogenases and cytochrome oxidase from Pseudomonas salinaria, an extreme halophile, are most active in high concentrations of sodium or potassium chloride. The lactic dehydrogenase and cytochrome oxidase of Micrococcus halodenitrificans are also more active at high concentrations of salt, but the isocitric, succinic, malic, α-ketoglutaric, and glutamic dehydrogenases of this moderate halophile are most active at much lower concentrations. It is concluded that the extreme halophiles have a high intracellular salt content. It is suggested that M. halodenitrificans maintains an intracellular salt concentration of about 0.5 M under optimal conditions for growth and that cytochrome oxidase is important in maintaining this level against a concentration gradient.