Purification and characterization of the intracellular ?-glucosidase from Aureobasidium sp ATCC 20524

Gene cloning and characterization of a novel salt-tolerant and glucose-enhanced β-glucosidase from a marine streptomycete

The gene BglNH encoding a β-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 β-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 pH6.0 and 45 °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 pH4.0 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.

Production optimization and properties of beta glucosidases from a marine fungus Aspergillus-SA 58

Aspergillus strain SA 58, showing considerable beta glucosidase production was selected as the potential strain. The fungus showed enzyme production in both acidic and alkaline pH. A temperature of 35 degrees C was found to be optimum for enzyme production. Maximum enzyme production was seen when pectin was used as the carbon source (80 U/ml). In solid-state fermentation, an enzyme production of 6200 U/g Initial Dry Substrate was noted. The strain produced two extra cellular enzymes and two intra cellular enzymes. For both the extra cellular enzymes (BGL A and BGL B), 60 degrees C was found to be optimum temperature for activity. BGL A showed an optimum pH of 4.0 while BGL B showed an optimum pH of 3.0 for activity. Both the enzymes showed a second peak of activity at pH 9.0. Both BGL A and BGL B showed high thermal stabilities with residual activities of 86% and 85% even after 6h of incubation at 50 degrees C.