Phytase gene expression in Lactobacillus and analysis of its biochemical characteristics

SummaryA 1.4-kb DNA containing the coding region of phytase gene from Aspergillus ficuum (A. ficuum) was connected with the plasmid of pIAβ8 to construct shuffling vector, which was inserted into Lactobacillus casei (L. casei) by electroporation. The Lactobacillus with phytase gene was selected and incubated in anaerobic liquid medium. The results indicated that the highest phytase activities in the supernatant and cells were 22.12 and 4.49 U ml−1 (P<0.05) at the fourth day of incubation; the optimum pH and temperature of phytase were 5.0 and 40–80 °C, respectively (P<0.05); the lowest pH value in the anaerobic medium was 3.35 (P<0.05) at the third day incubation; and the molecular weight of the expressed phytase was 39.2 kDa.