Expression of the Saccharomyces diastaticus STA1 Gene in Brewing Yeasts. K. Sakai, S. Fukui, S. Yabuuchi, S. Aoyagi, and Y. Tsumura, Central Research Laboratories, Asahi Breweries Ltd., Ohmore-kita 2-13-1, Ohta-ku, Tokyo 143, Japan. J. Am. Soc. Brew. Chem. 47:0087, 1989.

Molecular breeding of a highly attenuating brewing yeast was performed using recombinant DNA techniques. A hybrid plasmid YCpGSTA1 that carried the Saccharomyces diastaticus glucoamylase gene STA1 was constructed first. The STA1 gene was found to be expressed in a strain of S. carlsbergensis and two strains of brewing yeast. Glucoamylase was excreted into the culture medium by transformants harboring the STA1 gene. A trial microfermentation was carried out in flasks with wort, and the resulting young beer was analyzed. Real extract in the beer fermented by brewing yeast transformants harboring the STA1 gene was lower than in that fermented by the host.

Keywords: Brewing yeasts, Glucoamylase, Microfermentation, Saccharomyces diastaticus, Transformation