[Overexpression of artificial synthetic gene of Aspergillus niger NRRL3135 phytase in Pichia pastoris].

The phytase gene of Aspergillus niger NRRL3135 was modified with a deletion of intron and signal coding sequence. Then, according to the codon preference of Pichia pastoris, modified phyA gene was artificially synthesized and cloned into expression vector of pPICZ alpha A. The recombinant plasmid was transformed into chromosome of Pichia pastoris X-33 strain by electroporation. The results of SDS-PAGE and enzymatic kinetic analysis proved that the recombinant phytase was secreted into culture medium with nearly same character of natural phytase. After screening for high level productive yeast strains, a strain named SPAN-III produced recombinant phytase with 165,000 u/mL under the condition of shake cultivation. It will satisfy the demand for industrialized production in some degree.