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

ABSTRACT

AIMS: The purification and biochemical properties of the 1,4-ß-xylosidase of an oenological yeast were investigated. METHODS AND RESULTS: An ethanol-tolerant 1,4-ß-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-ß-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-ß-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-ß-xylosidase from P. membranifaciens to be used in the bioethanol production process.