Many microbes reduce the nitro substituents of 2,4,6-trinitrotoluene (TNT), producing aminodinitrotoluenes (ADNTs). These compounds are recalcitrant to further breakdown and are acutely toxic. In a search for organisms capable of metabolizing ADNTs, a bacterial strain was isolated for the ability to use 2-aminobenzoate (anthranilate) as sole C-source. This isolate, Pseudomonas aeruginosa MAO1, metabolized TNT by first reducing one nitro group to form either 2-amino-4,6-dinitrotoluene (2ADNT) or 4 -amino-2,6-dinitrotoluene(4ADNT). However, strain MA01 was distinct from other TNT-reducing organisms in that it transformed these compounds into highly polar metabolites through an 02-dependent process. Strain MAOl was able to cometabolize TNT, 2ADNT, and 4ADNT in the presence of a variety of carbon and energy sources. During aerobic cometabolism with succinate, 45% of uniformly ring-labeled [14C]TNT was transformed to highly polar compounds. Aerobic cometabolism of purified [14C]2ADN~ and [14C]4ADNT with succinate as C-source produced similar amounts of these polar metabolites. During 02-limited cometabolism with succinate as C-source and nitrate as electron acceptor, less than 8% of the [14C]TNT was transformed to polar metabolites. Purified 2,6-diamino-4 -nitrotoluene was not metabolized, and while 2,4-diamino-6-nitrotoluene was acetylated, the product (N-acetyl-2,4-diamino-6-nitrotoluene) was not further metabolized. Therefore, strain MAOl metabolized TNT by oxidation of the ADNTs and not by reduction the remaining nitro groups on the ADNTs.Key words: 2,4,6-trinitrotoluene, aminodinitrotoluene, Pseudomonas aeruginosa, cometabolism.Resume :Plusieurs microorganismes peuvent rCduire les substituants nitrks du 2,4,6-trinitrotolubne (TNT) avec production d'aminodinitrotoldnes (ADNTs). Ces composCs sont fortement toxiques et rksistent B une dCgradation plus poussCe. Dans une recherche d'organismes qui seraient capables de mktaboliser les ADNTs, nous avons isolk une bactkrie capable d'utiliser le 2-aminobenzoate (anthranilate) comme source unique de carbone. Cet isolat, le Pseudomonas aeruginosa MAOl, mCtabolisait le TNT par rkduction au dCpart du groupe nitro B partir du 2-amino-4,6-dinitrotoluene(2ADNT) ou du 4 -amino-2,6-dinitrotoluene(4ADNT). Cette souche MAOl Ctait cependant diffkrente des autres organismes capables de rCduire le TNT par le fait qu'elle transformait ces composCs en mCtabolites fortement polaires selon un processus dkpendant de 0 2 . Cette souche MAOl Ctait capable de co-mCtaboliser le TNT, le 2ADNT et le 4ADNT en prCsence de diverses sources de carbone et d'knergie. Lors du co-mCtabolisme aCrobie avec le succinate, on a mesurC que 45% du [14C]TNT uniformCment marquC sur I'anneau Ctait transform6 en composCs hautement polaires. Le co-mktabolisme en akrobiose du [14C]2ADNT et du [14C]4ADNT en presence du succinate comme seule source de C a produit des quantitks comparables de mktabolites polaires. Lors d'un co-mCtabolisme limit6 en 0 2 en prksence de succinate comme source de C et de nitrate ...