DEPOLYMERIZATION OF LOW-RANK COAL BY EXTRACELLULAR FUNGAL ENZYME-SYSTEMS .3. IN-VITRO DEPOLYMERIZATION OF COAL HUMIC ACIDS BY A CRUDE PREPARATION OF MANGANESE PEROXIDASE FROM THE WHITE-ROT FUNGUS NEMATOLOMA-FROWARDII B19

The in vitro depolymerization of humic acids derived from German ligni te (lour-rank coal, brown coal) was studied using: a manganese peroxid ase preparation ration from the white-rot fungus Nematoloma frowardii b19. The H2O2 required was continuously generated by glucose oxidase. Mn peroxidase depolymerized high-molecular-mass humic acids by forming fulvic-acid-like compounds. The depolymerization process was accompan ied by the decolorization of the dark-brown humic acid fraction solubl e in alkaline solutions (decrease in absorbance at 450 nm) and by the yellowish coloring of the fraction of acid-soluble fulvic-acid-like co mpounds (increase in absorbance at 360 nm). The Mn peroxidase of N. fr owardii b19 has been proved to be highly stable; even after an in vitr o reaction time of 7 days in the presence of humic acids, less than 10 % loss in total oxidizing activity was detectable.