Applied Biochemistry and Biotechnology, Vol.169, No.5, 1512-1522, 2013
Gene Cloning and Characterization of a Novel Salt-Tolerant and Glucose-Enhanced beta-Glucosidase from a Marine Streptomycete
The gene BglNH encoding a beta-glucosidase was cloned from a marine streptomycete. Sequence analysis revealed that BglNH encoded a 456-aa peptide with a calculated mass of 51 kDa. The deduced amino acid sequence of BglNH showed the highest identities of 61 % with known beta-glucosidases and contained a catalytic domain which belonged to the glycoside hydrolase family 1. The gene BglNH was expressed in Escherichia coli and the recombinant enzyme (r-BglNH) was purified. The optimum pH and temperature of r-BglNH were pH 6.0 and 45 A degrees C, respectively. The r-BglNH displayed the typical salt-tolerant and glucose-enhanced characteristics. Its activity was remarkably enhanced in the presence of 0.5 M NaCl (rose more than 1.6-fold) and 0.1 M glucose (rose more than 1.4-fold). Moreover, r-BglNH displayed good pH stability and metal tolerance. It remained stable after incubating with buffers from pH 4.0 to 10.0, and most metal ions had no significant inhibition on its activity. These properties indicate that r-BglNH is an ideal candidate for further research and industrial applications.