What is the role of microbes in gas hydrate formation and stability?

Glass, Jennifer B.

doi:10.1111/1462-2920.16252

Cited by 2 publications

(2 citation statements)

References 66 publications

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“…Gas hydrates, ice-like crystalline solids composed of water and hydrocarbons, are widely discovered in the deep subseafloor of every continental margin [ 1 , 2 ], typically hundreds of meters below the seafloor, e.g., the Hydrate Ridge [ 3 ] and Nankai Trough [ 4 , 5 ]. Ecological studies based on single marker genes have revealed abundant and diversified members of archaea and bacteria in the deep subsurface sediments associated with gas hydrates over the global ocean [ 3 – 7 ].…”

Section: Introductionmentioning

confidence: 99%

The majority of microorganisms in gas hydrate-bearing subseafloor sediments ferment macromolecules

et al. 2023

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Background Gas hydrate-bearing subseafloor sediments harbor a large number of microorganisms. Within these sediments, organic matter and upward-migrating methane are important carbon and energy sources fueling a light-independent biosphere. However, the type of metabolism that dominates the deep subseafloor of the gas hydrate zone is poorly constrained. Here we studied the microbial communities in gas hydrate-rich sediments up to 49 m below the seafloor recovered by drilling in the South China Sea. We focused on distinct geochemical conditions and performed metagenomic and metatranscriptomic analyses to characterize microbial communities and their role in carbon mineralization. Results Comparative microbial community analysis revealed that samples above and in sulfate-methane interface (SMI) zones were clearly distinguished from those below the SMI. Chloroflexota were most abundant above the SMI, whereas Caldatribacteriota dominated below the SMI. Verrucomicrobiota, Bathyarchaeia, and Hadarchaeota were similarly present in both types of sediment. The genomic inventory and transcriptional activity suggest an important role in the fermentation of macromolecules. In contrast, sulfate reducers and methanogens that catalyze the consumption or production of commonly observed chemical compounds in sediments are rare. Methanotrophs and alkanotrophs that anaerobically grow on alkanes were also identified to be at low abundances. The ANME-1 group actively thrived in or slightly below the current SMI. Members from Heimdallarchaeia were found to encode the potential for anaerobic oxidation of short-chain hydrocarbons. Conclusions These findings indicate that the fermentation of macromolecules is the predominant energy source for microorganisms in deep subseafloor sediments that are experiencing upward methane fluxes.

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Section: Introductionmentioning

confidence: 99%

The majority of microorganisms in gas hydrate-bearing subseafloor sediments ferment macromolecules

et al. 2023

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“…Bacterial CbpAs from ocean sediments hold promise for commercial application as eco-friendly substitutes for PVP and suggest that bacterial biomolecules may influence gas clathrate stability, with important repercussions for clathrate dissociation in warming oceans ( 40 ). Scaling up CbpA production as well as testing the efficacy of CbpAs on large volumes of natural gas clathrate is required before field use.…”

Section: Discussionmentioning

confidence: 99%

Molecular basis for inhibition of methane clathrate growth by a deep subsurface bacterial protein

Huard,

Johnson,

Fan

et al. 2023

PNAS Nexus

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Methane clathrates on continental margins contain the largest stores of hydrocarbons on Earth, yet the role of biomolecules in clathrate formation and stability remains almost completely unknown. Here we report new methane clathrate-binding proteins (CbpAs) of bacterial origin discovered in metagenomes from gas clathrate-bearing ocean sediments. CbpAs show similar suppression of methane clathrate growth as the commercial gas clathrate inhibitor polyvinylpyrrolidone and inhibit clathrate growth at lower concentrations than antifreeze proteins (AFPs) previously tested. Unlike AFPs, CbpAs are selective for clathrate over ice. CbpA3 adopts a non-globular, extended structure with an exposed hydrophobic surface, and, unexpectedly, its TxxxAxxxAxx motif common to AFPs is buried and not involved in clathrate binding. Instead, simulations and mutagenesis suggest a bipartite interaction of CbpAs with methane clathrate, with the pyrrolidine ring of a highly conserved proline residue mediating binding by filling empty clathrate cages. The discovery that CbpAs exert such potent control on methane clathrate properties implies that biomolecules from native sediment bacteria may be important for clathrate stability and habitability.

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What is the role of microbes in gas hydrate formation and stability?

Cited by 2 publications

References 66 publications

The majority of microorganisms in gas hydrate-bearing subseafloor sediments ferment macromolecules

The majority of microorganisms in gas hydrate-bearing subseafloor sediments ferment macromolecules

Molecular basis for inhibition of methane clathrate growth by a deep subsurface bacterial protein

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