Physico-Chemical Characterization of an Exocellular Sugars Tolerant Β-Glucosidase from Grape Metschnikowia pulcherrima Isolates

A broad variety of microorganisms with useful characteristics in the field of biotechnology live on the surface of grapes; one of these microorganisms is Metschnikowia pulcherrima. This yeast secretes a beta-glucosidase that can be used in fermentative processes to liberate aromatic compounds. In this work, the synthesis of an exocellular beta-glucosidase has been demonstrated and the optimal conditions to maximize the enzyme's effectiveness were determined. There was a maximum enzymatic activity at 28 degrees C and pH 4.5. Furthermore, the enzyme presents a great glucose and fructose tolerance, and to a lesser extent, ethanol tolerance. In addition, its activity was stimulated by calcium ions and low concentrations of ethanol and methanol. The impact of terpene content in wine was also determined. Because of these characteristics, beta-glucosidase is a good candidate for use in enology.