A yeast isolate able to produce high levels of extracellular alpha-amylase was selected from a collection of 385 yeasts and identified as Wickerhamia sp. by the sequence of the D1/D2 domain of the 26 S rDNA gene. Part of the nucleotide sequence of the amy1-W gene was cloned, and a sequence of 191 amino acids deduced from this gene was analyzed. The peptide contains three characteristic well-conserved regions in the active sites of alpha-amylases (EC 3.2.1.1). The enzyme was purified and in situ activity showed only one band with amylolytic activity. The molecular mass of the alpha-amylase was estimated at 54 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Enzymatic activity on soluble starch as substrate was optimal at pH 5-6 and 50 A degrees C. This thermostable enzyme was inhibited by EDTA-Na-2 and 1,10-phenanthroline; the activity of the dialyzed enzyme was reactivated with Ca2+ and Mg2+ cations, which indicates that the alpha-amylase is a metalloenzyme. alpha-Amylase production was induced by starch and maltose and repressed by glucose. The high yield and productivity found in this work makes this Wickerhamia sp. strain a promising candidate for the biotechnological production of alpha-amylase.