Tw. Sheremata et J. Hawari, Mineralization of RDX by the white rot fungus Phanerochaete chrysosporium to carbon dioxide and nitrous oxide, ENV SCI TEC, 34(16), 2000, pp. 3384-3388
Citations number
40
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
Biodegradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in liquid c
ultures (initially at 62 mg/L) was studied using the white rot fungus Phane
rochaete chrysosporium. With RDX as the main source of nitrogen, complete d
isappearance occurred after 60 d. The major products of RDX transformation
were CO2 and N2O, and both gases appeared after a 2-d lag period. Following
60 d, an average of 52.9% [UL-C-14]-RDX was mineralized to CO2, 10.7% was
taken up as biomass by the fungi, and 28.3% remained in the aqueous phase a
s unidentified metabolites. Of the nitrogen in RDX, 62.0% was transformed t
o N2O. Transformation of ring-labeled [N-15]-RDX, with subsequent analysis
by GC-MS, indicated that the N2O was composed of one nitrogen atom from the
RDX ring and the other nitrogen from one of the nitro group substituents.
Oxidation of RDX was correlated with manganese peroxidase (MnP) enzyme acti
vity (lignin peroxidase (LIP) activity was absent). Traces of 1-mononitroso
-3,5-dinitro-1,3,5-triazine were evident throughout the course of the exper
iment. Results of this study provide new information regarding N2O as a maj
or product of RDX mineralization. Quantification of N2O at sites contaminat
ed with RDX may be an important parameter for monitored natural attenuation
.