Electron shuttle-stimulated RDX mineralization and biological production of 4-nitro-2,4-diazabutanal (NDAB) in RDX-contaminated aquifer material

Man Jae Kwon, Kevin T. Finneran

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The potential for extracellular electron shuttles to stimulate RDX biodegradation was investigated with RDX-contaminated aquifer material. Electron shuttling compounds including anthraquinone-2,6-disulfonate (AQDS) and soluble humic substances stimulated RDX mineralization in aquifer sediment. RDX mass-loss was similar in electron shuttle amended and donor-alone treatments; however, the concentrations of nitroso metabolites, in particular TNX, and ring cleavage products (e. g., HCHO, MEDINA, NDAB, and NH4+) were different in shuttle-amended incubations. Nitroso metabolites accumulated in the absence of electron shuttles (i. e., acetate alone). Most notably, 40-50% of [14C]-RDX was mineralized to 14CO2 in shuttle-amended incubations. Mineralization in acetate amended or unamended incubations was less than 12% within the same time frame. The primary differences in the presence of electron shuttles were the increased production of NDAB and formaldehyde. NDAB did not further degrade, but formaldehyde was not present at final time points, suggesting that it was the mineralization precursor for Fe(III)-reducing microorganisms. RDX was reduced concurrently with Fe(III) reduction rather than nitrate or sulfate reduction. Amplified 16S rDNA restriction analysis (ARDRA) indicated that unique Fe(III)-reducing microbial communities (β- and γ-proteobacteria) predominated in shuttle-amended incubations. These results demonstrate that indigenous Fe(III)-reducing microorganisms in RDX-contaminated environments utilize extracellular electron shuttles to enhance RDX mineralization. Electron shuttle-mediated RDX mineralization may become an effective in situ option for contaminated environments.

Original languageEnglish
Pages (from-to)923-937
Number of pages15
JournalBiodegradation
Volume21
Issue number6
DOIs
Publication statusPublished - 2010 Nov 1

Keywords

  • Biodegradation
  • Bioremediation
  • Cyclic nitramine explosives
  • Electron shuttling
  • Fe(III) reducing microorganisms

ASJC Scopus subject areas

  • Environmental Engineering
  • Microbiology
  • Bioengineering
  • Environmental Chemistry
  • Pollution

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