ENHANCED EXPRESSION AND HYDROGEN-PEROXIDE DEPENDENCE OF LIGNIN PEROXIDASE FROM STREPTOMYCES-VIRIDOSPORUS T7A

The volumetric and specific activities of Streptomyces viridosporus T7 A lignin peroxidase isoform ALiP-P3 were increased by formulating a no vel corn-starch-based growth medium by optimizing the concentrations o f starch, casein, yeast extract, CaCO3, NH4Cl, and trace metals. This medium increases cell densities by 10-fold, cell-specific ALiP-P3 acti vity by 6-fold, and volumetric ALiP-P3 activity by 60-fold compared to those obtained using a yeast-extract-based medium. The presence of in creased concentrations of ALiP-P3 in the starch-based cultures was con firmed by Western blot analysis. In addition, the lignin peroxidase ac tivity was found to be highly dependent upon the concentration of the necessary cofactor, hydrogen peroxide; using 2,4-dichlorophenol as the substrate, ALiP-P3 activity increased 1448-fold as the concentration of H2O2 was varied from 0.1 to 250 mM.