Isolation and physiological characterization of yeasts involved in sorghum beer production

Yeasts responsible for sorghum beer fermentation were isolated and their physiological characteristics were studied. Twelve typical strains were identified in six beers and found to belong to genera Candida and Saccharomyces. Batch cultures of Candida krusei SO1, Saccharomyces cerevisiae LT3L1, Saccharomyces sp. LK3G and Saccharomyces cerevisiae LT1L2 were carried out in a synthetic glucose medium. The maximum growth rate and cell yield were dependent on incubation temperature and degree of aeration. Optimum temperature of culture was 30 degrees C for the four tested yeast strains. When grown on synthetic glucose medium and on natural sorghum medium they had a balanced amino acid profile, except for sulfur-containing amino acids. Considering their protein contents and their amino acid profiles, Candida krusei SO1 and Saccharomyces cerevisiae LT1L2 show some promise as an additive for human nutrition.