Production and characterization of extracellular α-amylase produced by wickerhamia sp. X-Fep

A yeast isolate able to produce high levels of extracellular a-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-Wgene 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 a-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 a-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 °C. This thermostable enzyme was inhibited by EDTA-Na2 and 1,10-phenanthroline; the activity of the dialyzed enzyme was reactivated with Ca ²⁺ + and Mg ²⁺ + cations, which indicates that the a-amylase is ametalloenzyme. a-Amylase productionwas induced by starch andmaltose 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 α-amylase.