The effect of succinate on the production of cloned glucoamylase by a recombinant yeast system was investigated. Saccharomyces cerevisiae was transformed with the 2 mu-based plasmid YEpSUCSTA containing the SUC2 promoter, the STA signal sequence, and the STA structural gene. Specific glucoamylase expression was 89% higher in a semi-synthetic medium containing succinate than in medium without succinate. This increase in glucoamylase activity in succinate-containing media reflects two roles of succinate; protection of rapid decrease in pH in the culture broth and enhancement of glucoamylase biosynthesis.