Molecular Cloning And Characterization Of A Novel Alkaline Beta-Glucosidase Encoding Gene (Kpybdn) From Klebsiella Pneumoniae, Performing A Conserved Function In Bacteria

Thermostable alkaline cellulases can resist high temperature and high pH, which make them widely applicable in the industries of food, detergent, paper making, and biomass utilization. To screen the effective beta-glucosidase coding genes from a thermostable alkaline cellulase-producing bacterium, using for constructing the enzyme engineering strains that can be employed in cellulose conversion and food production process. A thermostable alkaline cellulase-producing bacterium strain, Klebsiella pneumoniae strain SWU-27 was isolated and a novel alkaline beta-glucosidase encoding gene (kpYBDN) was cloned from its genomic DNA by using a shotgun-cloning method. kpYBDN was cloned into the expression vectors and transformed into E. coli strain BL21 for collecting the recombinant kpYBDN/his. The hydrolytic activity of the recombinant enzyme was determined by DNS method and it exhibited beta-glucosidase activity about 94.150 +/- 1.017 mU mL(-1). Then multiple sequence alignment and phylogenetic analysis showed that YBDNs had a high conservation and can conservatively exist in various bacterial strains. Finally, an additional analysis towards ecYBDN suggested that YBDN genes were common in genomes of different bacterial organisms and exhibited a conserved molecular function to hydrolyze disaccharide, Esculin. (C) 2015 Friends Science Publishers