Sequential biodegradation of TNT, RDX and HMX in a mixture

• Published in: Environmental pollution (1987) Vol. 157; no. 8; pp. 2231 - 2238
• Main Authors: Sagi-Ben Moshe, S., Ronen, Z., Dahan, O., Weisbrod, N., Groisman, L., Adar, E., Nativ, R.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.08.2009; Elsevier
• Subjects: Anaerobiosis; Applied sciences; Azocines - analysis; Azocines - chemistry; Azocines - metabolism; Biodegradation; Biodegradation, Environmental; Biological and physicochemical properties of pollutants. Interaction in the soil; Clostridium; cytotoxicity; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Explosive Agents - analysis; Explosive Agents - chemistry; Explosive Agents - metabolism; explosives; HMX; Pollution; Pollution, environment geology; RDX; Soil and sediments pollution; Soil Microbiology; soil microorganisms; Soil Pollutants - analysis; Soil Pollutants - chemistry; Soil Pollutants - metabolism; soil pollution; TNT; Toxicity; Triazines - analysis; Triazines - chemistry; Triazines - metabolism; Trinitrotoluene - analysis; Trinitrotoluene - chemistry; Trinitrotoluene - metabolism; Biodegradation; HMX; TNT; Toxicity; RDX; Microbial activity; Nitro compound; Nitrogen heterocycle; Multicomponent mixture; Metabolic pathway; Mutagen; Soil pollution; Octogen; Selfpurification; Hexogen; Aromatic compound; Microbial community; Organic compounds; Pollutant behavior; Trinitrotoluene; Denaturing gradient gel electrophoresis; Metabolic inhibitor; Microbial biomass; Polymerase chain reaction; Carcinogen; Unsaturated zone; Explosives
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2009.04.012

We describe TNT's inhibition of RDX and HMX anaerobic degradation in contaminated soil containing indigenous microbial populations. Biodegradation of RDX or HMX alone was markedly faster than their degradation in a mixture with TNT, implying biodegradation inhibition by the latter. The delay caused by the presence of TNT continued even after its disappearance and was linked to the presence of its intermediate, tetranitroazoxytoluene. PCR–DGGE analysis of cultures derived from the soil indicated a clear reduction in microbial biomass and diversity with increasing TNT concentration. At high-TNT concentrations (30 and 90 mg/L), only a single band, related to Clostridium nitrophenolicum, was observed after 3 days of incubation. We propose that the mechanism of TNT inhibition involves a cytotoxic effect on the RDX- and HMX-degrading microbial population. TNT inhibition in the top active soil can therefore initiate rapid transport of RDX and HMX to the less active subsurface and groundwater. TNT and its metabolites are cytotoxic for RDX and HMX-degrading bacteria in polluted soil.