Cyclic nitramine explosives biodegradation was investigated among four Fe(III)- and quinone-reducing bacterial genera. This strategy is an attractive option for RDX and/or HMX contamination because of their ubiquity; however, the biotransformation kinetics among different microbial populations is not known. The organisms investigated included two species within the Geobacteraceae, and one species each within the genera Anaeromyxobacter, Desulfitobacterium, and Shewanella. All species directly reduced RDX; however, humic substances (HS) and the HS analog anthraquinone-2,6-disulfonate (AQDS) significantly increased the rate and extent of RDX reduction. Degradation kinetics varied amongst the species tested, but extracellular electron shuttle mediated degradation rates were the fastest for each organism. RDX reduction rates ranged from 7.4 to 269.3 nmol RDX hr- 1 mg cell protein- 1 when AQDS was present. HMX was reduced more slowly by G. metallireducens than RDX; however, electron shuttles also stimulated HMX degradation. These data suggest that electron shuttle mediated cyclic nitramine transformation is ubiquitous among the keystone Fe(III)-reducing microbial genera, and that bioremediation strategies predicated on their physiology may be a reasonable approach in situ for both Fe(III)-rich and Fe(III)-poor environments.
Bibliographical noteFunding Information:
We thank Robert Sanford (University of Illinois, Geology) for providing cultures of Anaeromyxobacter and Desulfitobacterium. We thank Kelly Nevin (University of Massachusetts, Microbiology) for cultures of Geobacteraceae. We also thank Joseph W. Stucki (University of Illinois, Natural Resources and Environmental Sciences) for providing cultures ofShewanella. We thank Clint Arnett (USACE) for cyclic nitramine explosives. This work was supported by the Department of Defense Strategic Environmental Research and Development Program (SERDP) project number ER-1377.
- Electron shuttling
- Fe(III)-reducing microorganism
ASJC Scopus subject areas
- Environmental Chemistry
- Soil Science
- Health, Toxicology and Mutagenesis