Authors : Q.Q.Yin , Q. H. Zheng and X. T. Kang
Abstract: Phytase gene from A. niger was amplified by PCR and inserted into two plasmids (pPICZ? A and pGAPZ? A) to form two shuffle vector cassettes (Vppi and Vpga). P. pastoris were transformed by electroporation Phytase gene was expressed successfully in the host. After 4 d incubation in liquid media, phyatse activity in the supernatant reached the peak, 39.00 F/mL for P. pastoris with Vppi and 28.46 F/mL for P. pastoris with Vpga. They were increased by 51 folds for Vppi phytase and 37 folds for Vpga phytase, compared with the original A. niger (0.76 F/mL ). The analyses of biochemical characteristics of phytases showed that the optimum temperature and pH range were 30-50?C and 2.0-5.5, respectively. The optimum phytase concentrations for the inorganic phosphorous (P) released from soybean were 0.25 F/g soybean for Vppi phytase, 0.50-1.00 F/g for Vpga phytase and wild-type phytase. The expressed phytase from Vppi was better for thermostability and for P released at 0.25, 0.50 and 1.00 F/g soybean levels than Vpga phytase and wild-type phytase.
Q.Q.Yin , Q. H. Zheng and X. T. Kang , 2005. Phytase Gene Expression in Pichia pastoris and Analyses of its Biochemical Characteristics. International Journal of Molecular Medicine and Advance Sciences, 1: 116-120.