Production and partial characterization of a beta-amylase by Xanthophyllomyces dendrorhous

AIMS: The characterization of a beta-amylase produced by Xanthophyllomyces dendrorhous. METHODS AND RESULTS: Growth in different culture media showed that X. dendrorhous produces an amylase whose synthesis is repressed by the carbon source and induced by starch and maltose. Enzymatic assays using substrates with different degrees of polymerization together with viscosity experiments revealed that the enzyme was beta-amylase. According to the biochemical characterization, the enzyme has a molecular weight of 240 kDa and a Km of 1.35 mg ml-1. The optimum pH and temperature were 5.5 and 50 degrees C, respectively. Using different inhibitors of the enzymatic activity it was shown that cysteine, tryptophan and serine are essential amino acids for catalysis. CONCLUSIONS: Xanthophyllomyces dendrorhous CECT1690 synthesizes and secretes beta-amylase that could be a by-product, in addition to carotenoid pigments, in the fermentation downstream. SIGNIFICANCE AND IMPACT OF THE STUDY: The beta-amylase produced by X. dendrorhous may have certain industrial applications.