DECOLORIZATION OF AZO, TRIPHENYL METHANE, HETEROCYCLIC, AND POLYMERICDYES BY LIGNIN PEROXIDASE ISOENZYMES FROM PHANEROCHAETE-CHRYSOSPORIUM

The ligninolytic enzyme system of Phanerochaete chrysosporium decolori zes several recalcitrant dyes. Three isolated lignin peroxidase isoenz ymes (LiP 4.65, LiP 4.15, and LiP 3.85) were compared as decolorizers with the crude enzyme system from the culture medium. LiP 4.65 (H2), L iP 4.15 (H7), and LiP 3.85 (H8) were purified by chromatofocusing, and their kinetic parameters were found to be similar. Ten different type s of dyes, including azo, triphenyl methane, heterocyclic, and polymer ic dyes, were treated by the crude enzyme preparation. Most of the dye s lost over 75% of their color; only Congo red, Poly R-478, and Poly T -128 were decolorized less than the others, 54, 46, and 48%, respectiv ely. Five different dyes were tested for decolorization by the three p urified isoenzymes. The ability of the isoenzymes to decolorize the dy es in the presence of veratryl alcohol was generally comparable to tha t of the crude enzyme preparation, suggesting that lignin peroxidase p lays a major role in the decolorization and that manganese peroxidase is not required to start the degradation of these dyes. In the absence of veratryl alcohol, the decolorization activity of the isoenzymes wa s in most cases dramatically reduced. However, LiP 3.85 was still able to decolorize 20% of methylene blue and methyl orange and as much as 60% of toluidine blue 0, suggesting that at least some dyes can functi on as substrates for isoenzyme LiP 3.85 but not to the same extent for LiP 4.15 or LiP 4.65. Thus, the isoenzymes have different specificiti es towards dyes as substrates.