title: Highly glucose tolerant β-glucosidase from Aspergillus unguis: NII 08123 for enhanced hydrolysis of biomass.
abstract: Aspergillus unguis NII-08123, a filamentous fungus isolated from soil, was found to produce β-glucosidase (BGL) activity with high glucose tolerance. Cultivation of the fungus in different carbon sources resulted in the secretion of different isoforms of the enzyme. A low molecular weight isoform, which retained ~60 % activity in the presence of 1.5 M glucose, was purified to homogeneity and the purified enzyme exhibited a temperature and pH optima of 60 °C and 6, respectively. The K(m) and V(max) of the enzyme were 4.85 mM and 2.95 U/mg, respectively, for 4-nitrophenyl β-D-glucopyranoside. The glucose inhibition constant of the enzyme was 0.8 M, indicating high glucose tolerance, and this is the second-highest glucose tolerance ever reported from the Aspergillus nidulans group. The glucose-tolerant BGL from A. unguis, when supplemented to cellulase preparation from Penicillium, could improve biomass hydrolysis efficiency by 20 % in 12 h compared to the enzyme without additional beta glucosidase supplementation. The beta glucosidase from A. unguis is proposed as a highly potent "blend-in" for biomass saccharifying enzyme preparations.
authors.affiliation: Centre for Biofuels, Biotechnology Division, CSIR -National Institute for Interdisciplinary Science and Technology, Industrial Estate PO, Thiruvananthapuram, 695019, India.
authors.forename: Kuni Parambil
authors.initials: KP
authors.lastname: Rajasree
authors.forename: Gincy Marina
authors.initials: GM
authors.lastname: Mathew
authors.forename: Ashok
authors.initials: A
authors.lastname: Pandey
authors.forename: Rajeev Kumar
authors.initials: RK
authors.lastname: Sukumaran
mesh_terms: D001230:Aspergillus / Q000145:classification / Q000201:enzymology* / Q000302:isolation & purification / Q000378:metabolism; D018533:Biomass; D002480:Cellulase / Q000378:metabolism; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis / Q000187:drug effects; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D009596:Nitrophenols / Q000378:metabolism; D010407:Penicillium / Q000201:enzymology; D010802:Phylogeny; D013696:Temperature; D001617:beta-Glucosidase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D009596:Nitrophenols; C024719:4-nitrophenyl; D001617:beta-Glucosidase; D002480:Cellulase; D005947:Glucose