A new efficient expression system for Bacillus and its application to production of recombinant phytase

A new expression system was developed for Bacillus subtilis. This system us es a shuttle vector (B. subtilis - Eschericia coli) carrying a phosphate st arvation-inducible promoter (pst) and on a fed-batch cultivation strategy. The pst-promoter proved to be very strong and retain its tight regulation a lso when present on a multi-copy plasmid. The expression system developed s howed promising results when applied to the production of recombinant Bacil lus phytase - phytase activity at the end of cultivation reached 28.7 U ml( -1).