The extracellular amylolytic enzymes of Schwanniomyces alluvius were studied to determine future optimization of this yeast for the production of industrial ethanol from starch. Both at-amylase and glucoamylase were isolated and purified. a-Amylase had an optimum pH of 6.3 and was stable from pH 4.5 to 7.5. The optimum temperature for the enzyme was 40°C, but it was quickly inactivated at temperatures above 40°C. The Km for soluble starch was 0.364 mg/ml. The molecular weight was calculated to be 61,900 + 700. a-Amylase was capable of releasing glucose from starch, but not from pullulan. Glucoamylase had an optimum pH of 5.0 and was stable from pH 4.0 to >8.0. The optimum temperature for the enzyme was 50°C, and although less heat sensitive than a-amylase, it was quickly inactivated at 60°C. Km values were 12.67 mg/ml for soluble starch and 0.72 mM for maltose. The molecular weight was calculated to be 155,000 ± 3,000. Glucoamylase released only glucose from both soluble starch and pullulan. S. alluvius is one of the very few yeasts to possess both a-amylase and glucoamylase as well as some fermentative capacity to produce ethanol.

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