Solute Requirements for preventing Lysis of Some Marine Bacteria

Abstract

PREVIOUS work has revealed a specific requirement of a number of marine bacteria for sodium for growth^1,2 and oxidative metabolism^3,4. For optimum rate and extent of growth, 0.2–0.3 M Na⁺ was required though limited growth could occur after a sufficiently long incubation period at as low as 0.03 M Na⁺ (ref. 2). Since sucrose and K⁺ exerted only a slight sparing action on the Na⁺ requirement of the organisms examined it was concluded that the maintenance of an appropriate osmotic pressure in the medium was by no means the sole, or even the primary, function of Na⁺ in the growth of the cells. Nevertheless, cells of many of the species lysed quickly when washed in distilled water, and in the case of one of the species examined in more detail, lysis occurred also when cells were suspended in solutions containing sodium chloride and potassium chloride at concentrations of these salts that were optimum for growth. Lysis, however, did not occur when 0.05 Mg²⁺ or Mn²⁺ was included in the suspending medium³.