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FEMS Microbiol Ecol. 2018 Jun 1;94(6). doi: 10.1093/femsec/fiy064.

The hunt for the most-wanted chemolithoautotrophic spookmicrobes.

Author information

1
Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
2
Netherlands Earth System Science Center, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht, The Netherlands.
3
Department of Earth Sciences, Geochemistry, Utrecht University, Princetonlaan 8a, 3584 CB Utrecht, The Netherlands.
4
Soehngen Institute of Anaerobic Microbiology, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.

Abstract

Microorganisms are the drivers of biogeochemical methane and nitrogen cycles. Essential roles of chemolithoautotrophic microorganisms in these cycles were predicted long before their identification. Dedicated enrichment procedures, metagenomics surveys and single-cell technologies have enabled the identification of several new groups of most-wanted spookmicrobes, including novel methoxydotrophic methanogens that produce methane from methylated coal compounds and acetoclastic 'Candidatus Methanothrix paradoxum', which is active in oxic soils. The resultant energy-rich methane can be oxidized via a suite of electron acceptors. Recently, 'Candidatus Methanoperedens nitroreducens' ANME-2d archaea and 'Candidatus Methylomirabilis oxyfera' bacteria were enriched on nitrate and nitrite under anoxic conditions with methane as an electron donor. Although 'Candidatus Methanoperedens nitroreducens' and other ANME archaea can use iron citrate as an electron acceptor in batch experiments, the quest for anaerobic methane oxidizers that grow via iron reduction continues. In recent years, the nitrogen cycle has been expanded by the discovery of various ammonium-oxidizing prokaryotes, including ammonium-oxidizing archaea, versatile anaerobic ammonium-oxidizing (anammox) bacteria and complete ammonium-oxidizing (comammox) Nitrospira bacteria. Several biogeochemical studies have indicated that ammonium conversion occurs under iron-reducing conditions, but thus far no microorganism has been identified. Ultimately, iron-reducing and sulfate-dependent ammonium-oxidizing microorganisms await discovery.

PMID:
29873717
PMCID:
PMC5989612
DOI:
10.1093/femsec/fiy064
[Indexed for MEDLINE]
Free PMC Article

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