Purification and characterization of novel bi-functional GH3 family β-xylosidase/β-glucosidase from Aspergillus niger ADH-11

beta-Xylosidase plays an important role in xylan degradation by relieving the end product inhibition of endo-xylanase caused by xylo-oligosaccharides. beta-Xylosidase has a wide range of applications in food, feed, paper and pulp, pharmaceutical industries and in bioconversion of lignocellulosic biomass. Hence, in the present study focused on purification, biochemical characterization and partial sequencing of purified beta-xylosidase from xylanolytic strain Aspergillus niger ADH-11. Acetone precipitation followed by CPC using Sephacryl S-200 yielded 20.59-fold purified beta-xylosidase with 58.30% recovery. SDS-PAGE analysis of purified beta-xylosidase relieved a monomeric subunit with a molecular weight 120.48 kDa. Kinetic parameters of purified beta-xylosidase viz Km, Vmax, Kcat and catalytic efficiency were assessed. Purified beta-xylosidase was additionally active on p-nitrophenyl-beta-D-glucopyranoside substrate also. Moreover, peptide mass fingerprinting analysis support our biochemical studies and showed that the purified protein is a novel beta-xylosidase with beta-glucosidase activity and belongs to the bi-functional GH3 superfamily. Besides, tolerance of purified beta-xylosidase towards glucose and xylose was also assessed. (C) 2017 Elsevier B.V. All rights reserved.