NUTRITION OF PANDORINA MORUM1,2

A defined medium was developed for 3 strains of Pandorina morum. The strains tested required no vitamins or other organic compounds. The optimal initial pH was between 7.0 and 8.0. Various carbon sources were tested, and only glycolate and acetate appreciably stimulated growth. Mixotrophic growth in the light was stimulated by glycolate in all 3 strains, and by acetate in strains 880 and N76-6. Only strain N76-6 utilized acetate for heterotrophic growth in the dark. Thirty strains of P. morum of world-wide distribution were surveyed for mixotrophic and heterotrophic growth with acetate. All were found to fit 1 of 3 classes with respect to acetate metabolism: (1) no effect in light or dark; (2) stimulation of growth in light only; (3) stimulation of growth in light and dark.