Degradation of 2,4,6-trinitrotoluene by P. aeruginosa and characterization of some metabolites

Degradation of 2,4,6-trinitrotoluene (TNT), a nitroaromatic explosive found in the soil and ground water, was investigated using Pseudomonas aeruginosa in in vitro experiments. Biodegradable abilitiy of this bacteria was performed with 50 and 75 mg L−1 TNT concentrations in a defined liquid medium for 96 h time period. Treatment of TNT in supernatant samples taken at 0, 6, 12, 24, 48, 72 and 96 h from agitated vessels was followed by reverse-phase high-performance liquid chromatography (HPLC). In cultures supplemented with 50 and 75 mgL−1 TNT, after 96 h of incubation 46% and 59% reduction were detected respectively. Two metabolites as degradation intermediates with nitrite release into the medium, 2,4-dinitrotoluene (2,4-DNT) and 4-aminodinitrotoluene (4-ADNT), were elucidated by thin layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS). These findings clearly indicate that Pseudomonas aeruginosa can be used in bioremediation of TNT contaminated sites.

Phytoremediation of soil contaminated with cadmium and/or 2,4,6-trinitrotoluene.

Phytotoxicity, microbial activity, plant uptake and microbial degradation were examined using Rumex crispus in TNT and/or cadmium contaminated columns (TNT: 100 mg/kg of soil and Cd: 10 mg/kg of soil). The growth of plants was significantly inhibited by TNT, but not by Cd. The microbial activity was highly increased by plant root growth, decreased by Cd, and slightly reduced by TNT. The plant uptake of Cd was relatively well in Cd-contaminated column, but lowered by TNT in TNT+Cd-contaminated column. The microbial degradation of TNT occurred much faster in planted columns than in unplanted columns with minor effect of Cd (less 2-ADNT was produced). Therefore, it may be effective to treat TNT first and then Cd using phytoremediation in the TNT plus Cd contaminated sites.