TNT biotransformation potential of the clinical isolate of Salmonella typhimurium - potential ecological implications

Out of fifty-six isolates screened three bacterial strains enriched with TNT either as sole source of nitrogen (for Salmonella typhimurium, Klebsiella pneumoniae) or along with co-substrate (for Acinetobacter baumannii), have been carried out nitro group reduction under aerobic conditions. During studies, S. typhimurium found to have high potential (100% of 50 mg l-l) in removal of TNT, than K. pneumoniae (70% of 20 mg l-l) and A. baumannii (52% of 40 mg l-l, in presence of co-substrate). Therefore studies were focused on S. typhimurium, which had shown good growth, and protein contents, with disappearance of TNT, and concomitantly release of nitrite over the period of time. Removal of TNT was analyzed by HPLC, and nitrite liberation was consistently found coincided with TNT disappearance from the medium. As compared to earlier reports, 100% disappearance of TNT within 30 h by S. typhimurium is encouraging, and may indicate its potential in bioremediation of TNT. This is the first report on S. typhimurium, Klebsiella pneumoniae and Acinetobacter baumannii for transformation of TNT with nitrite release into the medium.