Characterization of a new multifunctional beta-glucosidase from Musca domestica.

OBJECTIVE: To engineer Pichia pastoris for heterologous production of cellulase from Musca domestica and explore its potential for industrial applications.

RESULTS: A new beta-glucosidase gene (bg), encoding 562 amino acids, was cloned from M. domestica by using rapid amplification of cDNA ends. The gene bg was linked to pPICZαA and expressed in P. pastoris with a yield of 500 mg l-1 . The enzyme has the maximum activity with 27.6 U mg-1 towards cellulose. The beta-glucosidase has stable activity from 20 to 70 °C and can tolerate one-mole glucose. It has the maximum activities for salicin (25.9 ± 1.8 U mg-1 ), cellobiose (40.1 ± 2.3 U mg-1 ) and cellulose (27.6 ± 3.5 U mg-1 ). The wide-range substrate activities of the beta-glucosidase were further verified by matrix-assisted laser desorption/ionization mass spectra. Structural analysis shows that the beta-glucosidase belongs to glycoside hydrolase family Ι and possesses O-glycosylation sites.

CONCLUSIONS: Thus, a multifunctional beta-glucosidase was expressed from M. domestica and provides a potential tool for industrial application of cellulose.