[Objective]The purpose was to study constitutive expression of the Phytase gene from Thermomyces sp.in Pichia pastoris.[Method]The Phytase gene from Thermomyces sp.without intron and signal peptide was amplified and cloned.The gene fragment was about 1.4 kb and had no intron and signal peptide.[Result]Sequence similarity analysis indicated Phytase gene cloned was similar to the Phytase gene from Thermomyces lanuginosis.DNA sequence similarity was 95%.The recombined plasmid p-phy T was transformed to Pichia ...