Publication Date:
2010-03-26
Description:
Only three biological pathways are known to produce oxygen: photosynthesis, chlorate respiration and the detoxification of reactive oxygen species. Here we present evidence for a fourth pathway, possibly of considerable geochemical and evolutionary importance. The pathway was discovered after metagenomic sequencing of an enrichment culture that couples anaerobic oxidation of methane with the reduction of nitrite to dinitrogen. The complete genome of the dominant bacterium, named 'Candidatus Methylomirabilis oxyfera', was assembled. This apparently anaerobic, denitrifying bacterium encoded, transcribed and expressed the well-established aerobic pathway for methane oxidation, whereas it lacked known genes for dinitrogen production. Subsequent isotopic labelling indicated that 'M. oxyfera' bypassed the denitrification intermediate nitrous oxide by the conversion of two nitric oxide molecules to dinitrogen and oxygen, which was used to oxidize methane. These results extend our understanding of hydrocarbon degradation under anoxic conditions and explain the biochemical mechanism of a poorly understood freshwater methane sink. Because nitrogen oxides were already present on early Earth, our finding opens up the possibility that oxygen was available to microbial metabolism before the evolution of oxygenic photosynthesis.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Ettwig, Katharina F -- Butler, Margaret K -- Le Paslier, Denis -- Pelletier, Eric -- Mangenot, Sophie -- Kuypers, Marcel M M -- Schreiber, Frank -- Dutilh, Bas E -- Zedelius, Johannes -- de Beer, Dirk -- Gloerich, Jolein -- Wessels, Hans J C T -- van Alen, Theo -- Luesken, Francisca -- Wu, Ming L -- van de Pas-Schoonen, Katinka T -- Op den Camp, Huub J M -- Janssen-Megens, Eva M -- Francoijs, Kees-Jan -- Stunnenberg, Henk -- Weissenbach, Jean -- Jetten, Mike S M -- Strous, Marc -- England -- Nature. 2010 Mar 25;464(7288):543-8. doi: 10.1038/nature08883.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Radboud University Nijmegen, IWWR, Department of Microbiology, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands. k.ettwig@science.ru.nl〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20336137" target="_blank"〉PubMed〈/a〉
Keywords:
*Anaerobiosis
;
Bacteria/classification/enzymology/genetics/*metabolism
;
Genome, Bacterial/genetics
;
Methane/*metabolism
;
Molecular Sequence Data
;
Nitrites/*metabolism
;
Oxidation-Reduction
;
Oxygen/metabolism
;
Oxygenases/genetics
;
Phylogeny
;
Soil Microbiology
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
,
Chemistry and Pharmacology
,
Medicine
,
Natural Sciences in General
,
Physics
