查看文章

Phytase is used as an animal feed additive that degrades phytic acid and reduces feeding costs and pollution caused by fecal excretion of phosphorus. Some phytases have been expressed in Pichia pastoris, among which the phytase from Citrobacter amalonaticus CGMCC 1696 had high specific activity (3548 U/mg). Improvement of the phytase expression level will contribute to facilitate its industrial applications.

To improve the phytase expression, we use modification of P _AOX1 and the α-factor signal peptide, increasing the gene copy number, and overexpressing HAC1 ⁱ to enhance folding and secretion of the protein in the endoplasmic reticulum. The genetic stability and fermentation in 10-L scaled-up fed-batch fermenter was performed to prepare for the industrial …