Zhang Yan, Xu Li, Huang Zhengnan and Yan Yunjun
Key Laboratory of Molecular Biophysics, The Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China
Aimed to major bottlenecks of high cost and low operation stability of free lipases, Candida rugosa lipase (CRL) and Rhizopus oryzae lipase (ROL) were co-displayed on the cell surface of Pichia pastoris and used as a whole-cell catalyst to produce biodiesel from tallow seed oil in this study. After screened by double resistance and tributyrin medium, the resultant co-displayed recombinant GS115/pRCS with the maximum activity of 470.59 U/g dry cells, being 3.9- and 1.3- fold compared with that of the single displayed ROL and CRL1, respectively. The analysis of fluorescence microscope and Flow Cytometer demonstrated that ROL and CRL1 were successfully co-displayed on the surface of recombinant P. pastoris GS115. When the self-immobilized lipases were utilized as whole cell catalysts, the rate of methyl ester from co-displayed recombinants strain GS115/pRCS harboring ROL and CRL1 is 1.4-fold compared with that of single displayed ROL. All these results indicate that biodiesel catalyzed by the co-displayed enzymes with synergetic effect could be an alternative strategy for producing biodiesel in low cost.
Keywords: Rhizopus oryzae lipase; Candida rugosa lipase 1; co-display; Pichia pastoris; whole-cell catalysts