B-Glucosidase from yeasts

ABSTRACT

Thirty two yeast strains belonging to different genera were screened for their ability to produce beta-glucosidase. The qualitative analysis showed' that only seven strains [21.9%] exhibited highest productivity while quantitative assay proved that kluyveromyces fragilis NRRL Y-1137 was the most resuhful strain. In addition, its beta-glucosidase was successfully purified by fractional precipitation with acetone. On the other hand, the properties of the partially purified enzyme obtained were as follows Optimum temperature of 50°, optimum pH value 6.2 and the rate of pNPG hydrolysis was linear up to 20 min under optimum assay conditions. Addition on cellobiosc or glucose to the reaction mixture decreased the enzyme activity. Furthermore, the enzyme was relatively more stable at pH 6.0-7.0 and rapidly inactivated at > 50°