Phytase Expressed by pIAβ8 and pGAPZαA Vectors and Analysis of its Biochemical Characters

Abstract

Phytase and phytase gene from Aspergillus ficuum (A. ficuum) were used in this study. The results showed that phytase activity reached the peak of 0.17 U/g after 4 d incubation in solid medium for A. ficuum; the optimum pH and temperature of phytase were 2.5 and 50 oC, respectively. A 1.4-kb DNA containing the coding region of phytase gene was isolated and inserted into the expression vectors of pIAβ8 and pGAPZαA, which were transformed into E. coli (Top 10). The maximal phytase activities in the supernatant and cells were 2.31 and 9.04 U/ml for the E. coli with pIAβ8, 8.04 and 2.93 U/ml for the E. coli with pGAPZαA, respectively. It was concluded that the recombinant of pIAβ8-phytase could express intracellular phytase, while the recombinant of pGAPZαA-phytase could express extracellular phytase. The molecular weight of phytase protein was 54.61 kDa.