Nutritional requirements of some marine luminous bacteria

Abstract

Photobacterium fischeri failed to grow in a salts glucose medium described previously as being suitable for the growth of photobacteria unless the buffer capacity of the medium was increased. This organism and a second strain of the same species grew and luminesced well if 0.1 M Tris buffer was added to the medium and the pH was adjusted to 7.5. Two other strains of Photobacterium failed to grow in this medium without the further addition of yeast extract. Complex mixtures of amino acids, vitamins, and other growth factors failed to replace yeast extract completely for the growth of either organism. The active component was not identified but some of its properties were determined. Passage of a solution of yeast extract through a cation exchange resin column failed to retain the active factor but succeeded in reducing contamination of the supplement by cations. This made it possible to prepare media for the growth of all four organisms sufficiently free of inorganic contaminants to permit the quantitative requirements of the organisms for Na+, K+, and Mg2+ to be determined. Three of the four Photobacteria required amounts of Na+ for optimum growth which were appreciably less than the requirements reported for other Gram-negative marine bacteria. The amounts of K+ and Mg2+ needed were similar to those required by other marine bacteria while Ca2+ showed no capacity to spare the Mg2+ requirement of P. fischeri.