International Journal of Molecular Sciences, Vol.15, No.1, 203-217, 2014
High-Level Expression of Pro-Form Lipase from Rhizopus oryzae in Pichia pastoris and Its Purification and Characterization
A gene encoding Rhizopus oryzae lipase containing prosequence (ProROL) was cloned into the pPICZ alpha A and electrotransformed into the Pichia pastoris X-33 strain. The lipase was functionally expressed and secreted in Pichia pastoris with a molecular weight of 35 kDa. The maximum lipase activity of recombinant lipase (rProROL) was 21,000 U/mL, which was obtained in a fed-batch cultivation after 168 h induction with methanol in a 50-L bioreactor. After fermentation, the supernatant was concentrated by ultrafiltration with a 10 kDa cut off membrane and purified with ion exchange chromatography using SP Sepharose Fast Flow chromatography. The optimum pH and temperature of the rProROL were pH 9.0 and 40 degrees C, respectively. The lipase was stable from pH 4.0 to 9.0 and from 25 to 55 degrees C. The enzyme activity was enhanced by Ca2+ and inhibited by Hg2+ and Ag+. The lipase showed high activity toward triglyceride-Tripalmitin (C16:0) and triglyceride-Trilaurin (C12:0).