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RESEARCH PRODUCT

Characterization of an ethanol-tolerant 1,4-β-xylosidase produced byPichia membranifaciens

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Aims:  The purification and biochemical properties of the 1,4-β-xylosidase of an oenological yeast were investigated. Methods and Results:  An ethanol-tolerant 1,4-β-xylosidase was purified from cultures of a strain of Pichia membranifaciens grown on xylan at 28°C. The enzyme was purified by sequential chromatography on DEAE cellulose and Sephadex G-100. The relative molecular mass of the enzyme was determined to be 50 kDa by SDS-PAGE. The activity of 1,4-β-xylosidase was optimum at pH 6·0 and at 35°C. The activity had a Km of 0·48 ± 0·06 mmol l−1 and a Vmax of 7·4 ± 0·1 μmol min−1 mg−1 protein for p-nitrophenyl-β-d-xylopyranoside. Conclusions:  The enzyme characteristics (pH and thermal stability, low inhibition rate by glucose and ethanol tolerance) make this enzyme a good candidate to be used in enzymatic production of xylose and improvement of hemicellulose saccharification for production of bioethanol. Significance and Impact of the Study:  This study may be useful for assessing the ability of the 1,4-β-xylosidase from P. membranifaciens to be used in the bioethanol production process.