High-level Expression of a Recombinant Thermostable Phytase in Bacillus subtilis

An efficient expression system was developed in Bacillus subtilis for the large scale production of phytase. The phytase gene with a native promoter derived from Bacillus amyloliquefaciens was cloned in the Bacillus expression vector pJH27 under a strong BJ27 promoter and its expression was optimized. The expression of the phytase gene occurred during late exponential growth and the extracellular phytase production was 2.0 units/ml, which constituted over 90% of the total protein. The yield was 100-fold higher than wild type Bacillus amyloliquefaciens DS11.