DEPOLYMERIZATION OF LOW-RANK COAL BY EXTRACELLULAR FUNGAL ENZYME-SYSTEMS .2. THE LIGNINOLYTIC ENZYMES OF THE COAL-HUMIC-ACID-DEPOLYMERIZINGFUNGUS NEMATOLOMA-FROWARDII B19

The production of ligninolytic enzymes was studied in surface cultures of the South American white-rot fungus Nematoloma frowardii b19 and f our other strains of this ecophysiological group (Clitocybula dusenii b11, Auricularia sp. m37a, wood isolates u39 and u45), which are able to depolymerize low-rank-coal-derived humic acids with the formation o f fulvic-acid-like compounds. The fungi produced the three crucial enz ymes of lignin degradation - lignin peroxidase, manganese peroxidase a nd laccase. In the case of N. frowardii b19, laccase and the two perox idases could be stimulated by veratryl alcohol. Manganese (II) ions (M n2+) caused a rapid increase of Mn peroxidase activity accompanied by the complete repression of lignin peroxidase. Under nitrogen-limited c onditions the growth as well as the production of ligninolytic enzymes was partly repressed. During the depolymerization process of coal hum ic acids using solid agar media, gradients of ligninolytic enzyme acti vities toward 2,2'-azinobis(3-ethylbenzthiazoline-6-sulphonate) and sy ringaldazine were detectable inside the agar medium.