Production, purification and characterization of an α‐amylase produced by Saccharomycopsis fibuligera

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Abstract
Saccharomycopsis fibuligera ST 2 produced high levels of extracellular amylase during the stationary phase of growth. Glucose or other low molecular weight metabolizable sugars did not repress the synthesis of the amylase, indicating the lack of catabolite repression in this organism. Of the nitrogen sources examined, yeast extract and corn steep liquor stimulated the highest yield of amylase. Ammonium sulphate inhibited α‐amylase synthesis. The enzyme was purified 118‐fold from the culture supernatant fluid by isopropanol precipitation and DEAE‐Sephadex A50 chromatography. The purified enzyme was characterized as an α‐amylase. The α‐amylase had the following properties: molecular weight, 40900 ± 500; optimum temperature, 60°C; activation energy, 1600 cal/mol; optimum pH, 4·8–6·0; range of pH stability, pH 4·0–9·4; Km (50°C, pH 5·5) for soluble starch, 0·572 mg/ml; final products of starch hydrolysis—glucose, maltose, maltotriose and maltotetraose.

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