An Unexpectedly Broad Thermal and Salinity-Tolerant Estuarine Methanogen Community

Blake, Lynsay I.; Sherry, Angela; Mejeha, Obioma K.; Leary, Peter; Coombs, Henry; Stone, Wendy; Head, Ian M.; Gray, Neil

doi:10.3390/microorganisms8101467

Cited by 4 publications

(1 citation statement)

References 47 publications

(72 reference statements)

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“…The over twofold increase in emissions was linked to disproportionate increase in methanogenesis activity, in comparison to other processes. Methanogenesis is known to strongly depend on temperature (Westermann et al, 1989;Schulz et al, 2006) and many methanogens may have a significantly higher optimum temperatures than their in situ habitat (Blake et al, 2020). Thus, a warming climate may favor methanogens and increase their activity, but the potential increase of methane production is difficult to link directly to higher emissions.…”

Section: Climate Change-induced Rising Temperatures and Sediment Biogeochemistrymentioning

confidence: 99%

Anthropogenic and Environmental Constraints on the Microbial Methane Cycle in Coastal Sediments

et al. 2021

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Large amounts of methane, a potent greenhouse gas, are produced in anoxic sediments by methanogenic archaea. Nonetheless, over 90% of the produced methane is oxidized via sulfate-dependent anaerobic oxidation of methane (S-AOM) in the sulfate-methane transition zone (SMTZ) by consortia of anaerobic methane-oxidizing archaea (ANME) and sulfate-reducing bacteria (SRB). Coastal systems account for the majority of total marine methane emissions and typically have lower sulfate concentrations, hence S-AOM is less significant. However, alternative electron acceptors such as metal oxides or nitrate could be used for AOM instead of sulfate. The availability of electron acceptors is determined by the redox zonation in the sediment, which may vary due to changes in oxygen availability and the type and rate of organic matter inputs. Additionally, eutrophication and climate change can affect the microbiome, biogeochemical zonation, and methane cycling in coastal sediments. This review summarizes the current knowledge on the processes and microorganisms involved in methane cycling in coastal sediments and the factors influencing methane emissions from these systems. In eutrophic coastal areas, organic matter inputs are a key driver of bottom water hypoxia. Global warming can reduce the solubility of oxygen in surface waters, enhancing water column stratification, increasing primary production, and favoring methanogenesis. ANME are notoriously slow growers and may not be able to effectively oxidize methane upon rapid sedimentation and shoaling of the SMTZ. In such settings, ANME-2d (Methanoperedenaceae) and ANME-2a may couple iron- and/or manganese reduction to AOM, while ANME-2d and NC10 bacteria (Methylomirabilota) could couple AOM to nitrate or nitrite reduction. Ultimately, methane may be oxidized by aerobic methanotrophs in the upper millimeters of the sediment or in the water column. The role of these processes in mitigating methane emissions from eutrophic coastal sediments, including the exact pathways and microorganisms involved, are still underexplored, and factors controlling these processes are unclear. Further studies are needed in order to understand the factors driving methane-cycling pathways and to identify the responsible microorganisms. Integration of the knowledge on microbial pathways and geochemical processes is expected to lead to more accurate predictions of methane emissions from coastal zones in the future.

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Section: Climate Change-induced Rising Temperatures and Sediment Biogeochemistrymentioning

confidence: 99%

Anthropogenic and Environmental Constraints on the Microbial Methane Cycle in Coastal Sediments

et al. 2021

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Organic matter accumulation drives methylotrophic methanogenesis and microbial ecology in a hypersaline coastal lagoon

Keneally,

Southgate,

Chilton

et al. 2024

Limnology & Oceanography

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Hypersalinity is common in coastal wetlands throughout warm, tropical, and arid regions. Climate‐induced changes in rainfall, sea level, and anthropogenic modification to basins and coastlines are likely to further increase salinization in these ecosystems. Yet, carbon cycling in hypersaline coastal wetlands is not well understood, and poorly constrained in climate models. In the Coorong, a eutrophic, hypersaline coastal lagoon, recognized as internationally important under the Ramsar convention, organic matter rapidly accumulates in deeper areas of the lagoon, through the settling of fine detrital particles, phytoplankton and suspended sediments. During initial surveys, elevated surface water methane (CH4) concentrations were observed above these fine depositional sediments. To identify the drivers of CH4 production, organic matter and sediment characteristics were assessed in surface sediments. Genetic markers (i.e., 16rDNA and the mcrA functional gene) were used to characterize microbial communities. With multiple lines of evidence, this study identifies organic matter, methanogen abundance, and salinity as important drivers of CH4 production, which is concentrated in depositional zones. Archaea were also more abundant in depositional zones, including methylotrophic methanogens: Methanofastidiosales, Methanomasiliicoccales, Methermicoccaceae, and Methanococcoides. These methanogens were highly correlated to CH4 in porewater, suggesting an influence of methylotrophic methanogenesis. To investigate further, metabolic genes were predicted from 16S rRNA with PICRUSt2. This represents the first effort to analyze CH4 dynamics in the Coorong, underscoring the need to integrate these unique ecosystems into global climate models to enhance our understanding of greenhouse gas dynamics and emissions in a changing climate.

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Factors deciding the assembly and thermostability of the DmrB cage

Garg

Sinha

2021

International Journal of Biological Macromolecules

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An Unexpectedly Broad Thermal and Salinity-Tolerant Estuarine Methanogen Community

Cited by 4 publications

References 47 publications

Anthropogenic and Environmental Constraints on the Microbial Methane Cycle in Coastal Sediments

Anthropogenic and Environmental Constraints on the Microbial Methane Cycle in Coastal Sediments

Organic matter accumulation drives methylotrophic methanogenesis and microbial ecology in a hypersaline coastal lagoon

Factors deciding the assembly and thermostability of the DmrB cage

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