Purification and characterization of a highly glucose tolerant β-glucosidase isozyme from Paecilomyces variotiiMG3

Abstract

Isolation and purification of a highly glucose tolerant β -glucosidase by a novel isolatePaecilomyces variotii MG3was achieved through a threestepspurification strategy. The purification steps used were ammonium sulphate fractionation, column chromatography using Sephacryl S 300 HR and anion exchange chromatography using DEAE-cellulose.The fungus produced two isozymes of β –glucosidase. Vmax values of isozyme I and II were 0.2497U/ml and 0.3519U/ml respectively. The Km value of isozyme I was 0.08839mM and that of isozyme II was 0.2710mM. Isozyme I exhibited a Ki of 901.6mM and was found to be insensitive to glucose concentration as high as 2M. The isozymes were tolerant to ethyl alcohol concentration up to 30% and displayed synergism with commercially available cellulase in cellulose degradation.