Increased production of tyrosinase from Bacillus megaterium strain M36 by the response surface method

The bacterial enzyme tyrosinase, with its high oxidizing capacity, can be applied in phenolic biotransformation, pharmaceutical, cosmetics and textile industries. In this research, a native Bacillus sp.-producing tyrosinase was isolated from a soil sample. The strain was identified by morphological, biochemical and molecular tests using bioinformatics analysis, and was named Bacillus megaterium strain M36. According to the blast analysis of 16S rDNA (1434 bp), the strain showed 99% identity with Bacillus megaterium DSM319. The production of tyrosinase from the isolated strain was optimized by classic and response surface methods (RSM). The optimal conditions for tyrosinase production by the strain were determined to be as follow: growth temperature 36°C, pH of medium 7.0, incubation time 16 h, with medium containing 0.4 mg/mL L-tyrosine, 0.05% yeast extract, 0.423% tryptone, 3.4% NaCl and 148.4 μM CuSO4. Results of experiments performed under the optimized condition showed an actual yield of 0.522 IU of enzyme, while the result under the initial conditions using basal medium (before optimization) gave 0.0312 IU of enzyme (16.7-fold increase). SDS-PAGE analysis showed that the tyrosinase enzyme from Bacillus megaterium strain M36 is about 34 kDa