ISOLATION, CHARACTERIZATION, MOLECULAR GENE CLONING, AND SEQUENCING OF A NOVEL PHYTASE FROM BACILLUS-SUBTILIS

The Bacillus subtilis strain VTT E-68013 was chosen for purification a nd characterization of its excreted phytase. Purified enzyme had maxim al phytase activity at pH 7 and 55 degrees C. Isolated enzyme required calcium for its activity and/or stability and was readily inhibited b y EDTA. The enzyme proved to be highly specific since, of the substrat es tested, only phytate, ADP, and ATP were hydrolyzed (100, 75, and 50 % of the relative activity, respectively), The phytase gene (phyC) was cloned from the B. subtilis VTT E-68013 genomic library. The deduced amino acid sequence (383 residues) showed no homology to the sequences of other phytases nor to those of any known phosphatases. PhyC did no t have the conserved RHGXRXP sequence found in the active site of know n phytases, and therefore PhyC appears not to be a member of the phyta se subfamily of histidine acid phosphatases but a novel enzyme having phytase activity. Due to its pH profile and optimum, it could be an in teresting candidate for feed applications.