BIOREMEDIATION OF TNT UNDER ANAEROBIC CONDITIONS: J. A. Hawari, 1 , 1 A. Halasz, 1 B. Spencer, 1 C. F. Shen, 1 S. Guoit, 1 C. W. Greer, 1 G. Sunahara, 1 G. Ampleman 2 and S. Thiboutot 2 1. Biotechnology Research Institute, National Research Council 6100 Royalmount Ave, Montreal (PQ) H4P 2R2 2. Defence Research Establishment Valcartier, National Defence, 2459 boul. Pie XI Nord, Val Bélair, PQ G3J 1X5 , Canada ABSTRACT: Most research conducted to biodegrade TNT under aerobic or anaerobic conditions has thus far shown that the explosive exhibited a reactivity towards biotransformation and a recalcitrance towards mineralization! This behavior from TNT, which distinguishes the explosive from others such as RDX and HMX, is partially attributed to the formation of reactive aromatic amines favoring, over mineralization, autocoupling, autooxidation, polymerization and binding to soil components and biomass. Most research conducted in our laboratories using aerobic and anaerobic bacteria and fungi showed rapid disappearance of TNT but with minimal mineralization. The present study describes the biotransformation of TNT (N-source) using anaerobic sludge supplemented with molasses (C-source). A combination of analytical techniques (SPME/GC-MS and LC/MS), identified two distinctive cycles in the degradation of TNT: the familiar stepwise reduction of TNT that produced triaminotoluene (TAT) in high yield (80 %) and the production of TAT azo-derivatives under anaerobic conditions (pH 7.0) despite the fact that this family of compounds breaks down anaerobically. If the microcosms containing TAT was exposed to air the production of phenolic compounds hudroxydiaminotoluene (HDAT) and dihydroxyaminotoluene (DHAT) were observed whose formation was enhanced under acidic conditions (pH 2-3). Experiments using 13 C-labeling showed that p-cresol and toluene were not formed, whereas 14 C- labeling showed only poor mineralization (<0.1%) despite the complete disappearance of TNT. E-mail Jalal.Hawari@NRC. Ca, Fax 514 496-6265, Tel 514 496-6267