Mineral requirements for the growth of Anabaena spiroides in vitro

Anabaena spiroides Klebahn, isolated from Upper Klamath Lake, Klamath County, Oregon, was cultured in Gerloff's modification of Chu's number 10 medium. Preliminary to a study of the major nutrient mineral requirements, the initial culture medium was modified by elimination of sodium silicate, the addition of Tris(hydroxymethyl)aminomethane, and the substitution of hydrogen ferric ethylenediamine di-o-hydroxyphenylacetate (EDDHA) for ferric citrate – citric acid.Provision of mineral nitrogen in the medium was found unnecessary for growth, strongly suggesting that A. spiroides can fix nitrogen, but final proof awaits the development of bacteria-free cultures. Although phosphorus was required in relatively high concentrations to obtain maximum growth, it was apparently accumulated in the cells, allowing them to survive long exposure in phosphorus-deficient media. Several other major elements either were required in very minute amounts or were accumulated by the alga. Iron provided in the alkaline-stable chelate EDDHA was required in lower concentration than in Gerloff's medium. A definite, high requirement for calcium was found.A balanced medium was developed that supported an increase of 100% in dry weight, 23% in chlorophyll content, and 10% in organic nitrogen above that obtained in the initial medium.