Thermophilic anaerobic oxidation of methane by marine microbial consortia - PubMed (original) (raw)

Thermophilic anaerobic oxidation of methane by marine microbial consortia

Thomas Holler et al. ISME J. 2011 Dec.

Abstract

The anaerobic oxidation of methane (AOM) with sulfate controls the emission of the greenhouse gas methane from the ocean floor. AOM is performed by microbial consortia of archaea (ANME) associated with partners related to sulfate-reducing bacteria. In vitro enrichments of AOM were so far only successful at temperatures ≤25 °C; however, energy gain for growth by AOM with sulfate is in principle also possible at higher temperatures. Sequences of 16S rRNA genes and core lipids characteristic for ANME as well as hints of in situ AOM activity were indeed reported for geothermally heated marine environments, yet no direct evidence for thermophilic growth of marine ANME consortia was obtained to date. To study possible thermophilic AOM, we investigated hydrothermally influenced sediment from the Guaymas Basin. In vitro incubations showed activity of sulfate-dependent methane oxidation between 5 and 70 °C with an apparent optimum between 45 and 60 °C. AOM was absent at temperatures ≥75 °C. Long-term enrichment of AOM was fastest at 50 °C, yielding a 13-fold increase of methane-dependent sulfate reduction within 250 days, equivalent to an apparent doubling time of 68 days. The enrichments were dominated by novel ANME-1 consortia, mostly associated with bacterial partners of the deltaproteobacterial HotSeep-1 cluster, a deeply branching phylogenetic group previously found in a butane-amended 60 °C-enrichment culture of Guaymas sediments. The closest relatives (Desulfurella spp.; Hippea maritima) are moderately thermophilic sulfur reducers. Results indicate that AOM and ANME archaea could be of biogeochemical relevance not only in cold to moderate but also in hot marine habitats.

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Figures

Figure 1

Figure 1

Rates of AOM in Guaymas Basin sediment at different temperatures measured as 14CH4 conversion to 14CO2. Homogenous samples (2–45 cm sediment depth, in situ temperature, 4–85 °C) were pre-incubated for 5 days at designated temperatures followed by incubation with labeled methane for 48 h. Error bars indicate s.d. from triplicates.

Figure 2

Figure 2

Time course experiment of AOM enrichment incubated without headspace at 50 °C. Sulfide formation (black circles) and methane consumption (black triangles) in the enrichment. A control without methane addition (open triangles, background methane) showed only minor sulfide formation (open circles).

Figure 3

Figure 3

Long-term enrichment of anaerobic methanotrophs at 50 °C. (a) Sulfide formation (black circles) in the initial sediment suspension and upon five exchanges of the sulfide-rich supernatant. Medium exchanges are indicated with arrows. (b) Linear (vertical bars) and semi-logarithmic (open circles) illustration of methane-dependent sulfide production of the different incubation periods over time; normalized by dry weights.

Figure 4

Figure 4

Phylotypes and cell aggregates in the methane-oxidizing anaerobic-enrichment culture grown at 50 °C. Phylogenetic trees showing the affiliations of 16S rRNA gene sequences retrieved from Guaymas methane-oxidizing enrichments with selected reference sequences of (a) Euryarchaeota and (b) Deltaproteobacteria. Sequences from this study are printed in bold red (archaea) and bold green (bacteria). Probe specificity is indicated with brackets. Bar=10% estimated sequence divergence. (c) Phylogenetic tree of amino acid sequences of the α subunit of the methyl-coenzyme M reductase (mcrA), (d–g) cell aggregates of ANME-1 visualized by CARD-FISH. Scale bars=10 μm. (d, e, g) Confocal laser scanning micrographs. (f) Regular epifluorescence micrograph. (d) Spherical ANME-1/HotSeep-1 aggregates stained with probe ANME-1-350 (red) and probe HotSeep-1-590 (green). (e) Monophyletic ANME-1 aggregate stained with probe ANME-1-350. (f) DAPI staining showing long chain-forming ANME-1 aggregates. (g) Chain-forming ANME-1/HotSeep-1 aggregates. ANME-1 cells were identified as members of subcluster ANME-1-Guaymas I (probe ANME-1-GI812, red) and bacterial partners as members of the HotSeep-1 cluster (probe HotSeep-1-590, green).

References

    1. Aeckersberg F, Bak F, Widdel F. Anaerobic oxidation of saturated hydrocarbons to CO2 by a new type of sulfate-reducing bacterium. Arch Microbiol. 1991;156:5–14.
    1. Aquilina A, Knab NJ, Knittel K, Kaur G, Geissler A, Kelly SP, et al. Biomarker indicators for anaerobic oxidizers of methane in brackish-marine sediments with diffusive methane fluxes. Org Geochem. 2010;41:414–426.
    1. Boetius A, Holler T, Knittel K, Felden J, Wenzhöfer F.2009The seabed as natural laboratory: lessons from uncultivated methanotrophsIn Epstein SS (ed),Microbiology Monographs: Uncultivated Microorganisms Springer: Berlin; 59–82.
    1. Boetius A, Ravenschlag K, Schubert CJ, Rickert D, Widdel F, Gieseke A, et al. A marine microbial consortium apparently mediating anaerobic oxidation of methane. Nature. 2000;407:623–626. - PubMed
    1. Bradley AS, Fredricks HF, Hinrichs K-U, Summons RE. Structural diversity of diether lipids in carbonate chimneys at the lost city hydrothermal field. Org Geochem. 2009;40:1169–1178.

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