Isolation and Characterization of a TNT-Degrading Bacterium

2,4,6-Trinitrotolene(TNT) is one extensively used explosive for various purposes and is harmful for soil and water. In the present study, four strains named as Thu-A, Thu-B, Thu-C and Thu-Z, were isolated from contaminated sites. Thu-Z had the highest degradation efficiency compare with other strains. It was identified by 16S rDNA assay that Thu-Z was a Pantone spp. The similarities in both biochemical properties and morphology to the representatives of Pantoea agglomerans suggested Thu-Z was Pantoea agglomerans strain. Thu-Z could use TNT as sole nitrogen source while cleavage NO₂ from nitroaromatic ring via direct aromatic ring reduction. Under nitrogen-limited condition, 96.6%N of TNT was used by Thu-Z for growth and with NaNO₂ as sole nitrogen source were done as compare. Also trace nitro reduction metabolites were identified. This meant that a dual pathway was found in Thu-Z, and direct aromatic ring reduction was predominant. Addition of other nitrogen source ((NH₄)₂SO₄) stimulated the growth of Thu-Z and accelerated TNT degradation.