Construction of an amylolytic industrial strain of Saccharomyces cerevisiae containing the Schwanniomyces occidentalis α-amylase gene

The gene encoding Schwanniomyces occidentalis α-amylase (AMY) was introduced into the chromosomal δ sequences of an industrial strain of Saccharomyces cerevisiae. To obtain a strain suitable for commercial use, an δ-integrative cassette devoid of bacterial DNA sequences was constructed that contains the AMY gene and aureobasidin A resistance gene (AUR1-C) as the selection marker. The AMY gene was expressed under the control of the alcohol dehydrogenase gene promoter (ADC1p). The α-amylase activity of Sacc. cerevisiae transformed with this integrative cassette was 6 times higher than that of Sch. occidentalis. The transformants (integrants) were mitotically stable after 100 generations in nonselective medium.