Disclosed is an isolated polypeptide comprising an amino acid sequence substantially as shown in SEQ ID NO:2, or substantially similar to an amino acid sequence encoded by a nucleotide sequence in a plasmid having all the identifying characteristics of Deposit No. FERM BP-6129. Also disclosed is an isolated polynucleotide substantially as shown in SEQ ID NO:1, or substantially similar to a nucleotide sequence contained in a plasmid having all of the identifying characteristics of Deposit No. FERM BP-6129. Further disclosed is an expression system comprising the above polynucleotide. Further disclosed is a composition comprising the above polypeptide.