DECOLORIZATION OF KRAFT BLEACHERY EFFLUENT CHROMOPHORES BY CORIOLUS-(TRAMETES)-VERSICOLOR

The white rot basidiomycete Coriolus (Trametes) versicolor has been shown to decolorize the stable high-molecular-weight chromophores released by kraft mill bleacheries. This report looks at the fungal requirements for optimal growth and decolorization, and the mechanism of chromophore degradation. Simple carbohydrates were shown to be essential for effective decolorization, and a medium composed of inexpensive industrial by-products provided excellent growth and decolorization. The decolorization activity was entirely O2-dependent, but unaffected by scavengers of O-2, OH, and H2O2. Free extracellular H2O2 was not necessary for E1 effluent decolorization. Decolorization was also not measurably repressed or induced by a variety of factors reportedly regulating lignin peroxidase expression and secondary metabolism in both C. versicolor and the related fungus Phanerochaete chrysosporium. These included veratryl alcohol, H2O2, nitrogen and carbon limitation, culture age, and elevated trace metals. No extracellular peroxidases or hydrogen peroxide could be detected during decolorization, although substantial levels of laccase-type phenol oxidases were present. Thus, it appears that E1 effluent decolorization by C. versicolor proceeds via a mechanism not employing secreted H2O2 and peroxidase. © 1990.