Biochemical characteristics and potential application of a novel ethanol and glucose-tolerant beta-glucosidase secreted by Pichia guilliermondii G1.2

beta-glucosidases are glycoside hydrolases that-particularly those from filamentous fungi-have been extensively explored in cellulose fiber saccharification and wine quality improvement. However, these enzymes from yeast have been poorly studied. In this study, an ethanol-glucose tolerant beta-glucosidase that is secreted by Pichia guilliermondii (current name Meyerozyma guilliermondii) was purified and characterized. This enzyme exhibited an estimated molecular mass of 97 kDa and the highest activity between pH 3.5-5.5 and 55 degrees C. The beta-glucosidase was also tolerant to acetone, ethanol, isopropanol, and methanol up to 30% and glucose at 1 M. It was also stable up to 55 degrees C for 80 min, maintaining 70% of its initial activity and in a wide pH range (pH 3-10). The enzyme exhibited 90-100% of its initial activity for 72 h at 20, 25, and 30 degrees C in presence of 10% ethanol at pH 3.5, which is a similar condition to winemaking. Studies that identify new enzymes and describe their purification are required for oenology applications. The beta-glucosidase described herein is a promising candidate for use in the preparation of wine. Additionally, its tolerance to glucose is an important biochemical property that adds value to this enzyme and enables it to be used during the final saccharification process. (AU)