Efficient one-step starch utilization by industrial strains of Saccharomyces cerevisiae expressing the glucoamylase and alpha-amylase genes from Debaryomyces occidentalis

摘要

Amylolytic industrial polyploid strains of Saccharomyces cerevisiae (ATCC 4126,ATCC 9763 and ATCC 24858) expressing a glucoamylase gene (GAM1) or an a-amylase gene (AMY) from Debaryomyces occidentalis were developed.The glucoamylase activity of S.cerevisiae ATCC 9763 expressing the GAM1 gene was 3.7-times higher than that of D.occidentalis.On the other hand,a-amylase activity in the corresponding strain expressing the D.occidentalis AMY gene increased 10-times relative to D.occidentalis.These two recombinant yeast strains expressing the GAM1 gene and AMY gene,respectively were cultured simultaneously to produce both glucoamylase and a-amylase for efficient one-step utilization of starch.Growth,substrate utilization and enzyme activity of these strains are described.