Articles | Volume 12, issue 3
https://doi.org/10.5194/bg-12-769-2015
https://doi.org/10.5194/bg-12-769-2015
Research article
 | 
10 Feb 2015
Research article |  | 10 Feb 2015

Characterization of incubation experiments and development of an enrichment culture capable of ammonium oxidation under iron-reducing conditions

S. Huang and P. R. Jaffé

Abstract. Incubation experiments were conducted using soil samples from a forested riparian wetland where we have previously observed anaerobic ammonium oxidation coupled to iron reduction. Production of both nitrite and ferrous iron was measured repeatedly during incubations when the soil slurry was supplied with either ferrihydrite or goethite and ammonium chloride. Significant changes in the microbial community were observed after 180 days of incubation as well as in a continuous flow membrane reactor, using 16S rRNA gene PCR-denaturing gradient gel electrophoresis, 454 pyrosequencing, and real-time quantitative PCR analysis. We be Acidimicrobiaceae bacterium A6), belonging to the Acidimicrobiaceae family, whose closest cultivated relative is Ferrimicrobium acidiphilum (with 92% identity) and Acidimicrobium ferrooxidans (with 90% identity), might play a key role in this anaerobic biological process that uses ferric iron as an electron acceptor while oxidizing ammonium to nitrite. After ammonium was oxidized to nitrite, nitrogen loss proceeded via denitrification and/or anammox.

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Short summary
Significant changes in the microbial community were observed during 180-day incubations of soil samples from a wetland where Feammox activity has been observed previously, as well as in a continuous flow membrane reactor. Results indicate that the dominant microbial species, an uncultured Acidimicrobiaceae bacterium A6 belonging to the Acidimicrobiaceae family, plays a key role in this anaerobic biological process using ferric iron as an electron acceptor while oxidizing ammonium to nitrite.
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