Abstract

Previous work documented complete perchlorate reduction in a membrane biofilm reactor (MBfR) using methane as the sole electron donor and carbon source. This work explores how the biofilm’s microbial community evolved as the biofilm stage-wise reduced different combinations of perchlorate, nitrate, and nitrite. The initial inoculum, carrying out anaerobic methane oxidation coupled to denitrification (ANMO-D), was dominated by uncultured Anaerolineaceae and Ferruginibacter sp. The microbial community significantly changed after it was inoculated into the CH4-based MBfR and fed with a medium containing perchlorate and nitrite. Archaea were lost within the first 40 days, and the uncultured Anaerolineaceae and Ferruginibacter sp. also had significant losses. Replacing them were anoxic methanotrophs, especially Methylocystis, which accounted for more than 25 % of total bacteria. Once the methanotrophs became important, methanol-oxidizing denitrifying bacteria, namely, Methloversatilis and Methylophilus, became important in the biofilm, probably by utilizing organic matter generated by the metabolism of methanotrophs. When methane consumption was equal to the maximum-possible electron-donor supply, Methylomonas, also an anoxic methanotroph, accounted for >10 % of total bacteria and remained a major part of the community until the end of the experiments. We propose that aerobic methane oxidation coupled to denitrification and perchlorate reduction (AMO-D and AMO-PR) directly oxidized methane and reduced NO3 to NO2 or N2O under anoxic condition, producing organic matter for methanol-assimilating denitrification and perchlorate reduction (MA-D and MA-PR) to reduce NO3 . Simultaneously, bacteria capable of anaerobic methane oxidation coupled to denitrification and perchlorate reduction (ANMO-D and ANMO-PR) used methane as the electron donor to respire NO3 or ClO4 directly. [Figure not available: see fulltext.]

Original languageEnglish (US)
Pages (from-to)1-9
Number of pages9
JournalEnvironmental Science and Pollution Research
DOIs
StateAccepted/In press - Feb 3 2016

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Keywords

  • Membrane-biofilm reactor
  • Methane oxidation
  • Microbial community
  • Perchlorate reduction

ASJC Scopus subject areas

  • Environmental Chemistry
  • Health, Toxicology and Mutagenesis
  • Pollution

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