Expression of Aspergillus oryzae phytase gene in Aspergillus oryzae RIB40 niaD−

Aspergillus oryzae RIB40 niaD− was transformed using a plasmid constructed with the A. oryzae phytase gene and pNAN8142 vector. The culture broth of the transformant, which was grown in a medium containing starch as a carbon source and polyvinylpyrrolidone showed phytase activity of a maximum of 2.0 units ml−1 at 37°C, pH 5.5.