Identification and characterization of a novel ?-glucosidase via metagenomic analysis of Bursaphelenchus xylophilus and its microbial flora.

ABSTRACT: ?-glucosidases catalyze the final step of cellulose hydrolysis and are essential in cellulose degradation. A ?-glucosidase gene, cen502, was identified and isolated from a metagenomic library from Bursaphelenchus xylophilus via functional screening. Analyses indicated that cen502 encodes a 465 amino acid polypeptide that contains a catalytic domain belonging to the glycoside hydrolase family 1 (GH1). Cen502 was heterologously expressed, purified, and biochemically characterized. Recombinant Cen502 displayed optimum enzymatic activity at pH 8.0 and 38?°C. The enzyme had highest specific activity to p-nitrophenyl-?-D-glucopyranoside (pNPG; 180.3 U/mg) and had K m and V max values of 2.334?mol/ml and 9.017 ?mol/min/mg, respectively. The addition of Fe2+ and Mn2+ significantly increased Cen502 ?-glucosidase activity by 60% and 50%, respectively, while 10% and 25% loss of ?-glucosidase activity was induced by addition of Pb2+ and K+, respectively. Cen502 exhibited activity against a broad array of substrates, including cellobiose, lactose, salicin, lichenan, laminarin, and sophorose. However, Cen502 displayed a preference for the hydrolysis of ?-1,4 glycosidic bonds rather than ?-1,3, ?-1,6, or ?-1,2 bonds. Our results indicate that Cen502 is a novel ?-glucosidase derived from bacteria associated with B. xylophilus and may represent a promising target to enhance the efficiency of cellulose bio-degradation in industrial applications.

SUBMITTER: Zhang L 

PROVIDER: S-EPMC5665999 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature