Production of a fungal protein, Taka-amylase A, by protein-producing Bacillus brevis HPD31

An expression-secretion vector, pMK300, was constructed to express theAspergillus oryzae Taka-amylase A (Taa) cDNA. The promoter and signal peptide regions of the HWP (a major cell wall protein ofBacillus brevis HPD31) gene on pMK300 were efficiently utilized inB. brevis HPD31 and a large amount of Taa (22 mg/l) was secreted into the medium. The HWP signal peptide utilized for secretion of Taa was correctly processed during the protein transport across the membrane. The enzymatic properties of Taa produced byB. brevis HPD31 were the same as those of theAspergillus oryzae Taa in several respects; specific activity thermal and pH stabilities, and temperature and pH optima. These results, in combination with previous results, indicate thatB. brevis HPD31 could be used to produce extracellularly foreign proteins of diverse orgins as functional proteins.