Abstract
Microbial lipases could be used to hydrolyze or recombine fats and oils, and had great applications in food processing, bioenergy and chemical industry. Mucor circinelloides was an important gamma-linolenic acid producing strain, and its genome was predicted to contain a large number of genes encoding lipases, the key enzymes in lipid metabolism. In the present study, a potential lipase WJ_23 from Mucor circinelloides WJ11 was cloned for the first time and heterologously expressed and purified to homogeneity in Pichia pastoris. By SDS-PAGE analysis, the molecular weight of the recombinant lipase was estimated to be ~ 34 kDa. The optimal temperature and pH of the recombinant lipase were 50 °C and 9.0, respectively. The recombinant lipase had good thermal stability at 50 °C with a broad pH stability from 6.0 to 11.0. After incubation at 37 °C for 24 h, the activity of the recombinant lipase remained over 95% between pH 7.0 and 9.0. The recombinant lipase possessed a preference for the long chain substrates. Using p-NPP as substrate, the measured kinetic parameters V(max) and K(m) were 94.34 U/mg and 6.37 mmoL/L, respectively. In addition, the activity of the recombinant lipase was not affected obviously by various metal ions, and it exhibited certain stability and tolerance towards several kinds of organic solvents. This research might provide a basis for the further industrial application of recombinant M. circinelloides lipase.