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Nat Commun. 2014 Jul 7;5:4346. doi: 10.1038/ncomms5346.

Methane production by phosphate-starved SAR11 chemoheterotrophic marine bacteria.

Author information

1
1] Department of Microbiology, Oregon State University, Corvallis, Oregon 97331, USA [2] [3].
2
1] College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon 97331, USA [2].
3
Department of Microbiology, Oregon State University, Corvallis, Oregon 97331, USA.

Abstract

The oxygenated surface waters of the world's oceans are supersaturated with methane relative to the atmosphere, a phenomenon termed the 'marine methane paradox'. The production of methylphosphonic acid (MPn) by marine archaea related to Nitrosopumilus maritimus and subsequent decomposition of MPn by phosphate-starved bacterioplankton may partially explain the excess methane in surface waters. Here we show that Pelagibacterales sp. strain HTCC7211, an isolate of the SAR11 clade of marine α-proteobacteria, produces methane from MPn, stoichiometric to phosphorus consumption, when starved for phosphate. Gene transcripts encoding phosphonate transport and hydrolysis proteins are upregulated under phosphate limitation, suggesting a genetic basis for the methanogenic phenotype. Strain HTCC7211 can also use 2-aminoethylphosphonate and assorted phosphate esters for phosphorus nutrition. Despite strain-specific differences in phosphorus utilization, these findings identify Pelagibacterales bacteria as a source of biogenic methane and further implicate phosphate starvation of chemoheterotrophic bacteria in the long-observed methane supersaturation in oxygenated waters.

PMID:
25000228
DOI:
10.1038/ncomms5346
[Indexed for MEDLINE]

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