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

Abstract

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 50kDa 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±0·06mmol l(-1) and a Vmax of 7·4±0·1μmol 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.

Keywords: 1,4‐β‐xylosidase; Pichia membranifaciens; characterization; ethanol tolerant; purification.