Effective Degradation of 2,4,6-Trinitrotoluene (TNT) with a Bacterial Consortium Developed from High TNT-degrading Bacteria Isolated from TNT-contaminated Soil

Özet

Öz In this study, bacterial strains, capable of using TNT as a nitrogen source, were isolated from TNT-contaminated soil samples collected from military region in Kırıkkale, Turkey. We selected three strains that showed the highest TNT degradation capacity and according to 16S rRNA sequence analysis, the strains were identified as Klebsiella pneumoniae (designated SC1 K1, showed 99% homology), Raoultella planticola (designated SC1 K4, showed 99% homology) and Pseudomonas putida (designated SC1 K5, showed 99% homology). These strain were cultured in medium containing 100 mg L-1 TNT, SC1 K1 degraded 90 % of the initial TNT, SC1 K4 degraded 95 % of the initial TNT, and SC1 K5 degraded 84 % of the initial TNT after 24 h of incubation. Then, to remove TNT more efficiently, we constructed a bacterial consortium with these strains. The developed consortium was cultured in medium containing 100 mg L-1 TNT and the consortium removed 97.2 % of the initial TNT after four-hour incubation period. According to HPLC analyses, The consortium transformed TNT to 2-amino-4,6- dinitrotoluene, 4-amino-2,6-dinitrotoluene and an unknown metabolite. The isolates showed high TNT degradation capacity compared to many previous studies and the developed bacterial consortium can be used to remediate the TNT-contaminated environments.