Transformation and mineralization of 2,4,6-trinitrotoluene (TNT) by manganese peroxidase from the white-rot basidiomycete Phlebia radiata

The degradation of the nitroaromatic pollutant 2,4,6-trinitrotoluene (TNT) by the manganese-dependent peroxidase (MnP) of the white-rot fungus Phlebia radiata and the main reduction products formed were investigated. In the p resence of small amounts of reduced glutathione (10 mM), a concentrated cel l-free preparation of MnP from P. radiata exhibiting an activity of 36 nkat /ml (36 nmol Mn(II) oxidized per sec and per ml) transformed 10 mg/l of TNT within three days. The same preparation was capable of completely transfor ming the reduced derivatives of TNT. When present at 10 mg/l, the aminodini trotoluenes were transformed in less than two days and the diaminonitrotolu enes in less than three hours. Experiments with C-14-U-ring labeled TNT and 2-amino-4,6-dinitrotoluene showed that these compounds were mineralized by 22% and 76%, respectively, within 5 days. Higher concentrations of reduced glutathione (50 mM) led to a severe inhibition of the degradation process. It is concluded that Phlebia radiata is a good candidate for the biodegrad ation of TNT as well as its reduction metabolites.