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Analysis of methanotrophic bacteria in Movile Cave by stable isotope probing

Analysis of methanotrophic bacteria in Movile Cave by stable isotope probing
Analysis of methanotrophic bacteria in Movile Cave by stable isotope probing
Movile Cave is an unusual groundwater ecosystem that is supported by in situ chemoautotrophic production. The cave atmosphere contains 1-2% methane (CH4), although much higher concentrations are found in gas bubbles that keep microbial mats afloat on the water surface. As previous analyses of stable carbon isotope ratios have suggested that methane oxidation occurs in this environment, we hypothesized that aerobic methane-oxidizing bacteria (methanotrophs) are active in Movile Cave. To identify the active methanotrophs in the water and mat material from Movile Cave, a microcosm was incubated with a 10%13CH4 headspace in a DNA-based stable isotope probing (DNA-SIP) experiment. Using improved centrifugation conditions, a 13C-labelled DNA fraction was collected and used as a template for polymerase chain reaction amplification. Analysis of genes encoding the small-subunit rRNA and key enzymes in the methane oxidation pathway of methanotrophs identified that strains of Methylomonas, Methylococcus and Methylocystis/Methylosinus had assimilated the 13CH4, and that these methanotrophs contain genes encoding both known types of methane monooxygenase (MMO). Sequences of non-methanotrophic bacteria and an alga provided evidence for turnover of CH4 due to possible cross-feeding on 13C-labelled metabolites or biomass. Our results suggest that aerobic methanotrophs actively convert CH4 into complex organic compounds in Movile Cave and thus help to sustain a diverse community of microorganisms in this closed ecosystem.
1462-2920
111-120
Hutchens, Elena
0d67a944-e86c-484d-936d-d18365c14430
Radajewski, Stefan
7b004805-0cf8-409b-9951-a76319b7d733
Dumont, Marc G.
afd9f08f-bdbb-4cee-b792-1a7f000ee511
McDonald, Ian R.
7a0278c5-e2dd-440a-9a2a-f3b820dd65ca
Murrell, J. Colin
244a92ff-dbe1-41cf-9e65-baacbc4a90cf
Hutchens, Elena
0d67a944-e86c-484d-936d-d18365c14430
Radajewski, Stefan
7b004805-0cf8-409b-9951-a76319b7d733
Dumont, Marc G.
afd9f08f-bdbb-4cee-b792-1a7f000ee511
McDonald, Ian R.
7a0278c5-e2dd-440a-9a2a-f3b820dd65ca
Murrell, J. Colin
244a92ff-dbe1-41cf-9e65-baacbc4a90cf

Hutchens, Elena, Radajewski, Stefan, Dumont, Marc G., McDonald, Ian R. and Murrell, J. Colin (2004) Analysis of methanotrophic bacteria in Movile Cave by stable isotope probing. Environmental Microbiology, 6 (2), 111-120. (doi:10.1046/j.1462-2920.2003.00543.x). (PMID:14756876)

Record type: Article

Abstract

Movile Cave is an unusual groundwater ecosystem that is supported by in situ chemoautotrophic production. The cave atmosphere contains 1-2% methane (CH4), although much higher concentrations are found in gas bubbles that keep microbial mats afloat on the water surface. As previous analyses of stable carbon isotope ratios have suggested that methane oxidation occurs in this environment, we hypothesized that aerobic methane-oxidizing bacteria (methanotrophs) are active in Movile Cave. To identify the active methanotrophs in the water and mat material from Movile Cave, a microcosm was incubated with a 10%13CH4 headspace in a DNA-based stable isotope probing (DNA-SIP) experiment. Using improved centrifugation conditions, a 13C-labelled DNA fraction was collected and used as a template for polymerase chain reaction amplification. Analysis of genes encoding the small-subunit rRNA and key enzymes in the methane oxidation pathway of methanotrophs identified that strains of Methylomonas, Methylococcus and Methylocystis/Methylosinus had assimilated the 13CH4, and that these methanotrophs contain genes encoding both known types of methane monooxygenase (MMO). Sequences of non-methanotrophic bacteria and an alga provided evidence for turnover of CH4 due to possible cross-feeding on 13C-labelled metabolites or biomass. Our results suggest that aerobic methanotrophs actively convert CH4 into complex organic compounds in Movile Cave and thus help to sustain a diverse community of microorganisms in this closed ecosystem.

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Accepted/In Press date: 5 October 2003
Published date: February 2004
Organisations: Centre for Biological Sciences, Environmental

Identifiers

Local EPrints ID: 387956
URI: http://eprints.soton.ac.uk/id/eprint/387956
ISSN: 1462-2920
PURE UUID: 17f33cbe-5873-4f21-a7df-b8c00b797f9c
ORCID for Marc G. Dumont: ORCID iD orcid.org/0000-0002-7347-8668

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Date deposited: 25 Jan 2017 16:20
Last modified: 15 Mar 2024 03:53

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Contributors

Author: Elena Hutchens
Author: Stefan Radajewski
Author: Marc G. Dumont ORCID iD
Author: Ian R. McDonald
Author: J. Colin Murrell

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