Purification and Characterization of a Novel β-1,3-1,4-Glucanase (Lichenase) from Thermophilic Rhizomucor miehei with High Specific Activity and Its Gene Sequence

Production, purification, and characterization of a novel beta-1,3-1,4-glucanase (lichenase) from thermophilic Rhizomucor miehei CAU432 were investigated. High-level extracellular beta-1,3-1,4-glucanase production of 6230 U/mL was obtained when oat flour (3%, w/v) was used as a carbon source at 50 degrees C. The crude enzyme was purified to homogeneity with a specific activity of 28818 U/mg. The molecular weight of purified enzyme was estimated to be 35.4 kDa and 33.7 kDa by SDS PAGE and gel filtration, respectively. The optimal pH and temperature of the enzyme were pH 5.5 and 60 degrees C, respectively. The Km values of purified beta-1,3-1,4-glucanase for barley beta-glucan and lichenan were 2.0 mM and 1.4 mM, respectively. Furthermore, the gene (RmLic16A) encoding the beta-1,3-1,4-glucanase was cloned and its deduced amino acid sequence showed the highest identity (50%) to characterized beta-1,3-1,4-glucanase from Paecilomyces thermophila. The high-level production and biochemical properties of the enzyme enable its potential industrial applications.