Enrichment and Isolation of Methanol-Oxidizing Yeasts and Bacteria with Special Reference to Cell Yields and Amino Acid Content

Abstract

Summary Yeasts and bacteria, utilizing methanol as carbon source, were isolated from different samples (soil affected by sulphite waste water, waste water purification system, ooze from an eutrofic lake, soil, peat). Cell yields, yield coefficients, and crude protein content of 18 different yeast strains and 9 different bacterial strains isolated were investigated, and the amino acid composition of 5 yeast strains and 2 bacterial strains, supplying high cell yields, was also investigated. Yeasts produced 5–62 mg. of cell mass per 100 ml. of medium. The yield coefficients were good on the average, 6 strains had 30–50%. Bacteria grew better than yeasts in relative terms. 33–144 mg. of cells were produced per 100 ml. of medium. The yield coefficients were relatively low. No strain contained all the essential amino acids in amounts needed by man. The strains investigated did, however, contain most of these to a sufficient extent in relation to the amino acids of the reference protein of FAO (Protein requirements 1965).