NUTRITION AND METABOLISM OF MARINE BACTERIA: VI. QUANTITATIVE REQUIREMENT FOR HALIDES, MAGNESIUM, CALCIUM, AND IRON

Abstract

A study has been made of the specificity of the requirement of some marine bacteria for halides, magnesium, calcium, and iron and of their quantitative requirements for these ions in the presence and absence of related ions.All of the organisms investigated either required or responded to the addition of Cl⁻ to the medium. Br⁻ could replace Cl⁻ but somewhat less readily, while I⁻ was toxic. For organism B-16, which required the addition of Mg⁺⁺ but not Ca⁺⁺ to the medium, the amount of Mg⁺⁺ required for maximum growth varied with the level of Ca⁺⁺ present. At low levels, a marked sparing action of Ca⁺⁺ was evident, while at higher concentrations of Ca⁺⁺ some antagonism between the ions was detected. Sr⁺⁺ also spared the Mg⁺⁺ requirement of this organism. For B-9, which required both Mg⁺⁺ and Ca⁺⁺, Mg⁺⁺ could be shown to spare the need for Ca⁺⁺.An absolute requirement of one organism for Fe⁺⁺ was demonstrated. Ni⁺⁺ and Co⁺⁺ showed no sparing action and proved to be toxic at a level at which Fe⁺⁺ produced an optimum growth response.