Production of Ethanol from Starch by Recombinant Saccharomyces Cerevisiae Strain Expressing the Alpha-amylase Gene

Shwanniomyces occidentalis possess highly efficient alpha amylase activity that enable this yeast to use raw starch as an carbon source. S.occidentalis alpha amylase gene was cloned into the Saccharomyces cerevisiae under the control of different powerful constitutive promoters, ADH1, GPD and TEF. So that the recombinant strains which carries the same gene under the control of different promoters showed different level of expression. Then, the starch utilization power of these strains compared in aerobic and anaerobic conditions. The final results showed that recombinant strain with Alpha amylase gene under the control of ADH1 promoter could produce up to 2.3% g/l ethanol from 5% starch. The pleasant work demonstrates a new approach for improving ethanol production by regulating the expression level of one enzyme instead of using different enzymes, modified enzymes or combining several enzymes.