Remediation potential of a soil bacterium, Planomicrobium flavidum (S5-TSA-19) for 2,4,6-trinitrotoluene (TNT) i.e., a nitro-aromatic explosive in aquatic medium.

Abstract

2,4,6-Trinitrotoluene (TNT), a nitro-aromatic explosive commonly used for defence and several non-violent applications is contributing to serious environmental pollution problems including human health. The current study investigated the remediation potential of a native soil isolate i.e., Planomicrobium flavidum (strain S5-TSA-19) against TNT. At a TNT concentration of 120 mg/L with a specified environment, the isolate remained incubated for 30 days in a minimal salt medium (MSM). Regular growth of the isolate, the concentration of TNT, nitrate, nitrite and ammonium ion were evaluated at a particular time during the experiment. Within 168 hours (i.e., 7 days) of incubation, P. flavidum co-metabolically degraded 100% TNT. The biodegradation procedure succeeded the first order kinetics mechanism. Formation of additional metabolites like 2,4-dinitrotoluene (DNT), 2,4-diamino-6-nitrotoluene (2-DANT) and 2-amino-4,6-dinitrotoluene (2-ADNT), were also witnessed. TNT seems to be non-toxic for the isolate, as it reproduced magnificently in explosive presence. For TNT degradation, the nitro-reductase enzyme was observed to be responsible. This is so far the first reporting of Planomicrobium flavidum, efficiently bioremediating TNT i.e., a nitro-aromatic compound via different degradation pathways, leading to the production of simpler as well as less harmful end products. Further, in the near future, at the field scale application Planomicrobium flavidum may be explored for the bioremediation of TNT (i.e., a nitroaromatic- compound) contaminated effluents.