ISOLATION AND CHARACTERIZATION OF A SULFATE-REDUCING BACTERIUM THAT REMOVED TNT (2,4,6-TRINITROTOLUENE) UNDER SULFATE-REDUCING AND NITRATE-REDUCING CONDITIONS

A sulfate-reducing bacterium isolated from a creek sediment and capabl e of metabolizing TNT (2,4,6-trinitrotoluene) using sulfate and nitrat e as electron accepters was tentatively characterized as Desulfovibrio desulfuricans strain A. The isolate was unable to use TNT as the sole source of carbon. TNT degradation was accomplished by a co-metabolic process using pyruvate as the main substrate. Two different metabolic steps were employed by this isolate under different electron-accepting conditions. Under sulfate-reducing conditions, TNT was reduced to 4-a mino-2,6-dinitrotoluene, 2-amino-4,6-dinitrotoluene and 2,4-diamino-6- nitrotoluene. In contrast, under nitrate-reducing conditions, these am ino compounds were not produced, instead butyric acid was identified a s the major metabolite of TNT metabolism. This organism also used a wi de variety of other carbon sources, including ethanol lactate, succina te, formate and malate. The isolate contained the electron-carrier des ulfoviridin and used sulfate, nitrate, and thiosulfate as electron acc eptors. The isolate had an optimal temperature of 25 degrees C and an optimal pH of 6.8 and used ammonium chloride, nitrate and glutamate as nitrogen sources. The characteristic features of the sulfate-reducing bacterium closely resembled those of Desulfovibrio desulfuricans. Cop yright (C) 1996 Elsevier Science Ltd.