Biodegradation of TNT by microbes isolated from contaminated sites

Abstract

Explosives are highly toxic chemical compounds holding high contents of oxygen and nitrogen which expands on ignition to generate a tremor movement that applies high pressure on the adjacent environment, triggering a detonation and exiting lethal waste into the environment (Singh at al. 2012). 2,4,6-Trinitrotoluene (TNT), a nitro-aromatic explosive commonly used for defense and several non-violent applications. Numerous recognized physical and chemical abiotic technologies are existing, but bioremediation occurred as a green substitute. Therefore, bioremediation of TNT is a significant step to attenuate the prevailing problem. The existing study explored the aptitude of 04 native isolate i.e., Indiicoccus explosivorum isolate S5-TSA-19, Microbacterium esteraromaticum isolate SL1-DS-TSB-4, Pelomonas aquatica isolate WS2-R2A-65 and Psuedarthrobacter chlorophenolicus isolate S5-TSA-26, subjected to remediate TNT. All the 04 bacterial strains were isolated from gathered samples of an explosive production site. All four isolates were assessed for their degradation proficiency of 120 mg/L TNT in minimal salt medium inside an optimized conditions (i.e., at 30- 35°C), all the isolates were constantly incubated for 25 days. Bacterial growth, nitrite, nitrate, ammonium and residual explosive concentrations were monitored. The four isolates showed positive growth in presence of TNT. Co-metabolically, all the four isolates degraded 100% TNT. TNT appears to be non-lethal for the isolates, as they reproduced admirably in TNT presence as depicted by their morphology analysis via SEM. During TNT degradation, formation of supplementary metabolites were evaluated through LC-MS peaks.. On the assessment of these results, it is proposed that all the 4 isolates i.e., P. chlorophenolicus, I. explosivorum, P. aquatica, and M. esteraromaticum followed combined pathways (aerobic and anaerobic) for degradation heading towards the formation of simpler as well as less damaging end products.