Protein enrichment of grain sorghum by submerged culture of the amylolytic yeastsSchwanniomyces occidentalis andLipomyces kononenkoae

Cultivation of aSchwanniomyces occidentalis derepressed mutant in a 10% (w/v) gelatinized grain sorghum slurry increased the crude protein content of the biomass from an initial value of 12% to 41% (dry) within 20 h, with no detectable residual starch. Co-cultivation ofCandida utilis with theS. occidentalis mutant improved the final crude protein content to 47% within 18 h, whereas a co-culture ofC. utilis with aLipomyces kononenkoae mutant resulted in a cultivation time of 50 h with a significantly lower protein content and a low final -amylase activity. In a 15% (w/v) grain sorghum slurry aC. utilis/S. occidentalis co-culture increased the protein content to about 44% within 30 h. Yeast cultivation increased the lysine and threonine content of the final biomass considerably.