Isolation and characterization of novel multifunctional recombinant family 26 glycoside hydrolase from Mehsani buffalo rumen metagenome

Rumen microbiota harbor a diverse set of carbohydrate-active enzymes (CAZymes), which play a crucial role in the degradation of a complex plant polysaccharide thereby providing metabolic energy to the host animals. Earlier, we reported CAZYme analysis from the buffalo rumen metagenome by high throughput shotgun sequencing. Among the various CAZymes, glycoside hydrolase family 26 (GH26) enzymes have a number of industrial applications including in paper, oil, biofuel, food, feed, pharmaceutical, coffee, and detergent industries. Here, we report isolation and characterization of GH26 enzyme from the buffalo rumen metagenome. A novel GH26 gene composed of 1,119 base pairs was successfully amplified using the gene-specific primers inferred based on the contig generated from metagenome sequence assembly and cloned in a pET32a (+) expression vector as an N-terminal histidine tag fusion protein. A novel GH26 protein from an unknown rumen microorganism shared a maximum of 68% identity with the Prevotella ruminicola 23 encoded carbohydrate esterase family 7 and 46% with Bacteroides sp. 2_1_33B encoded mannan endo-1, 4--mannosidase. The recombinant GH26-histidine tag fusion protein was expressed in Escherichia coli and purified using Ni-NTA affinity chromatography. The purified enzyme displayed multifunctional activities against various carbohydrate substrates including locust bean gum, beechwood xylan, pectin, and carboxymethyl cellulose suggesting mannanase, xylanase, pectin esterase, and endoglucanase activities, respectively.