MASS-BALANCE STUDIES WITH C-14-LABELED 2,4,6-TRINITROTOLUENE (TNT) MEDIATED BY AN ANAEROBIC DESULFOVIBRIO SPECIES AND AN AEROBIC SERRATIA SPECIES

Investigations were carried out to evaluate the level of incorporation of radiolabeled 2,4,6-trinitrotoluene (TNT) and metabolites into the bacterial biomass of two different bacterial species after cometabolic ally mediated TNT transformation. Biotransformation experiments with C -14-TNT indicated that TNT was not mineralized; however, carbon derive d from TNT became associated with the cells. It was found that more th an 42% of the initially applied radiolabel was associated with the cel l biomass after cometabolic C-14-TNT transformation with the strictly anerobic Desulfovibrio species strain SHV, whereas with the strictly a erobic Serratia plymuthica species strain B7, 32% of cell-associated C -14 activity was measured. The remainder of the radiolabel was present in the supernatants of the liquid cultures in the form of different T NT metabolites. Under anoxic conditions with the Desulfovibrio species , TNT was ultimately transformed to 2,4,6-triaminotoluene (TAT) and bo th diaminonitrotoluene isomers, whereas under oxic conditions with the Serratia species, TNT was converted to hydroxylaminodinitrotoluenes a nd aminodinitrotoluenes, with 4-amino-2,6-dinitrotoluene (4ADNT) being the major end product. In both culture supernatants, small amounts of very polar, radiolabeled, but unidentified metabolites were detected. At the end of the experiments approximately 92% and 96% of the origin ally applied radioactivity was recovered in the studies with the Serra tia and Desulfovibrio species, respectively.