TRANSFORMATION OF INDUSTRIAL DYES BY MANGANESE PEROXIDASES FROM BJERKANDERA-ADUSTA AND PLEUROTUS-ERYNGII IN A MANGANESE-INDEPENDENT REACTION

We investigated the transformation of six industrial azo and phthalocy anine dyes by ligninolytic peroxidases from Bjerkandera adusta and oth er white rot fungi. The dyes were not oxidized or were oxidized very l ittle by Phanerochaete chrysosporium manganese peroxidase (MnP) or by a chemically generated Mn3+-lactate complex. Lignin peroxidase (LiP) f rom B. adusta also showed low activity with most of the dyes, but the specific activities increased 8- to 100-fold when veratryl alcohol was included in the reaction mixture, reaching levels of 3.9 to 9.6 U/mg, The B. adusta and Pleurotus eryngii MnP isoenzymes are unusual becaus e of their ability to oxidize aromatic compounds like 2,6-dimethoxyphe nol and veratryl alcohol in the absence of Mn2+. These Mnp isoenzymes also decolorized the azo dyes and the phthalocyanine complexes in an M n2+-independent manner. The reactions with the dyes were characterized by apparent ii, values ranging from 4 to 16 mu M and specific activit ies ranging from 3.2 to 10.9 U/mg, Dye oxidation by these peroxidases was not increased by adding veratryl alcohol as it was in LIP reaction s. Moreover, the reaction was inhibited by the presence of Mn2+, which in the case of Reactive Black 5, an azo dye which is not oxidized by the Mn3+-lactate complex, was found to act as a noncompetitive inhibit or of dye oxidation by B. adusta MnP1.