AROMATIC NITROREDUCTASE FROM THE BASIDIOMYCETE PHANEROCHAETE-CHRYSOSPORIUM

A membrane-associated aromatic nitroreductase activity was identified in cell-free extracts of the lignin-degrading fungus Phanerochaete chr ysosporium. The enzyme catalyzed the nitro group reduction of 1,3-dini trobenzene, 2,4-dinitrotoluene, 2,4,6-trinitrotoluene, 1-chloro-2,4-di nitrobenzene, and 2,4-dichloro-1-nitrobenzene. The corresponding hydro xylamines and/or amines were identified as reaction products by HPLC a nd/or GC-MS. 1-Nitroso-3-nitrobenzene and 1-hydroxylamino-3-nitrobenze ne also were reduced by the enzyme, suggesting they were intermediates in the reaction. The enzyme required NAD(P)H as a cosubstrate and the optimal pH and temperature for the reaction were 6.5 and 50 degrees C , respectively. Enzyme activity was not observed in the presence of mo lecular oxygen. The membrane-associated enzyme could be solubilized wi th the nonionic detergent Triton X-100. (C) 1994 Academic Press, Inc.