Yeast conversion of mango waste or methanol to single cell protein and other metabolites

The utilization of methanol or mango-waste hydrolyzate by Pichia pinus was studied with respect to the biomass, single cell protein and other metabolites. Optimum cultural conditions on both substrates were 30°C and pH 4·8–5. The maximum yield was obtained at the third day of growth (3·6 g/litre in methanol medium, 6·2 g/litre in mango-peel extract medium). At the end of the logarithmic phase, methanol yeast cells contained 52·2% crude protein, 36% true protein and 14·2% nucleic acids, while cells grown on mango-peel extract contained 62·2% crude protein, 39% true protein and 12·9% nucleic acids. The amino acid composition of the protein, especially of the essential acids, was comparable to FAO standards. α-Ketoglutaric and pyruvic acids were found in cells from both substrates but dihydroxyacetone was found in high quantity in methanol medium (976·9 μg%) while acetoacetic acid was found only in mango-peel medium (244·4 μg%).