Aerobic and anaerobic biodegradation of TNT by newly isolated Bacillus mycoides

A TNT-degrading strain, which was isolated from Fe-reducing bacterial consortia and was identified as Bacillus mycoides based on its 16S rDNA sequence, was first used to degrade TNT under aerobic or anaerobic conditions. The results shows that 93% of the initial TNT was degraded after 16 h under aerobic environment, while 94% of TNT was reduced after 24 h under anaerobic environment. This is attributed to slower microorganism growth under anaerobic conditions and was confirmed in a biokinetic study, where lower degradation rates were obtained under anaerobic condition. Two TNT degradation metabolites, 4-amino-2,6-dinitrotoluene and 6-amino-2,4-dinitrotoluene, were identified by GC–MS and the degradation pathways of TNT by B. mycoides were proposed. Finally, B. mycoides was used to degrade TNT in industrial wastewater, where more than 88% of the TNT was removed, irrespective of the aerobic or anaerobic conditions.

► Biodegradation of TNT by Bacillus mycoides is firstly observed.
► Biodegradation of TNT under either aerobic or anaerobic conditions.
► Degradation pathways of TNT by B. mycoides were proposed.
► More than 88% of the TNT in wastewater was removed.