Coal-bed methane is one of the largest unconventional natural gas resources. Although microbial activity may greatly contribute to coal-bed formation, it unclear whether complex aromatic organic compounds present in coal can be used for methanogenesis. We show that deep subsurface-derived Methermicoccus methanogens produce from more than 30 types methoxylated (MACs) as well coals containing MACs. In contrast known methanogenesis pathways involving one- and two-carbon compounds, this...

Summary The methanogenic communities and pathways in a high‐temperature petroleum reservoir were investigated through incubations of the production water crude oil, combined with radiotracer experiments molecular biological analyses. conducted without any substrate amendment under pressurized conditions that mimicked situ environment (55°C, 5 MPa). Changes methane acetate concentrations during indicated stoichiometric from acetate. Rates hydrogenotrophic methanogenesis measured using [ 14...

Abstract A key feature that differentiates prokaryotic cells from eukaryotes is the absence of an intracellular membrane surrounding chromosomal DNA. Here, we isolate a member ubiquitous, yet-to-be-cultivated phylum ‘ Candidatus Atribacteria’ (also known as OP9) has intracytoplasmic apparently nucleoid. The isolate, RT761, subsurface-derived anaerobic bacterium appears to have three lipid membrane-like layers, shown by cryo-electron tomography. Our observations are consistent with classical...

Gas hydrates deposited in subseafloor sediments are considered to primarily consist of biogenic methane. However, little evidence for the occurrence living methanogens has been provided. This study investigated viable methanogen diversity, population, physiology and potential activity hydrate-bearing (1-307 m below seafloor) from eastern Nankai Trough. Radiotracer experiments, quantification coenzyme F430 molecular sequencing analysis indicated methanogenic predominance hydrogenotrophic...

Anaerobic oxidation of methane (AOM) in marine sediments is an important global sink, but the physiological characteristics AOM-associated microorganisms remain poorly understood. Here we report cultivation AOM microbial community from deep-sea methane-seep sediment using a continuous-flow bioreactor with polyurethane sponges, called down-flow hanging sponge (DHS) bioreactor. We anaerobically incubated collected Nankai Trough, Japan, for 2,013 days at 10°C. Following incubation, active...

We investigated methane production and oxidation the depth distribution phylogenetic affiliation of a functional gene for methanogenesis, methyl coenzyme M reductase subunit A (mcrA), at two sites Integrated Ocean Drilling Program Expedition 311. These sites, U1327 U1329, are respectively inside outside area gas hydrate on Cascadia Margin. Radiotracer experiments using (14)C-labelled substrates indicated high potential rates in hydrate-bearing sediments [128-223 m below seafloor (mbsf)]...

Non-methanotrophic bacteria such as methylotrophs often coexist with methane-oxidizing (methanotrophs) by cross-feeding on methane-derived carbon. Methanol has long been considered a major compound that mediates of Despite the potential importance in global carbon cycle, only few studies have actually explored metabolic responses when methanotroph. Recently, we isolated novel facultative methylotroph, Methyloceanibacter caenitepidi Gela4, which grows syntrophically methanotroph,...

Microbial methane oxidation has a significant impact on the flux from marine gas hydrate areas. However, environmental fate of remains poorly constrained. We quantified relative contributions aerobic and anaerobic methanotrophs to consumption in sediments hydrate-bearing Sakata Knoll, Japan, by situ geochemical microbiological analyses coupled with 13C-tracer incubation experiments. The ANME-1 ANME-2 species contributed 33.2 1.4% fluxes at 0–10 10–22 cm below seafloor (bsf), respectively....

A novel anaerobic, thermophilic bacterium of the class Atribacteria, strain M15T, was isolated from a high-temperature gas reservoir, Japan. Cells M15T were gram-negative, short oval-shaped, and lacked flagella. Growth occurred at 45–75 °C (optimum 70–75 °C) pH 6.5–8.5 7.5–8.0) fast under optimal conditions (doubling time 11.4 h). Yeast extract required for growth. Fermentative growth with glucose, arabinose, xylose, cellobiose observed. The major fermentative end products glucose acetate...

Methanogen diversity and methanogenic potential in formation water obtained from the Minami-kanto gas field Japan were investigated by using 16S rRNA gene libraries culture-based enrichment methods, respectively. This region is largest that produces natural gases of dissolved-in-water type Japan. Although microbial population density was below statistical quantification limits (1 × 104 cells ml−1), autofluorescent coccoid rod-shaped indicative methanogens observed. The represented genera...

Summary Anaerobic methane‐oxidizing archaea (ANME) are known to play an important role in methane flux, especially marine sediments. The 16S rRNA genes of ANME have been detected terrestrial freshwater subsurfaces. However, it is unclear whether actively involved oxidation these environments. To address this issue, Holocene sediments the subsurface Kanto Plain Japan were collected for biogeochemical and molecular analysis. potential activity anaerobic (AOM) (0.38–3.54 nmol cm −3 day −1 ) was...

A mesophilic, slightly halophilic, obligately methylotrophic, methanogenic archaeon, designated strain GTA13(T), was isolated from natural gas-bearing confined aquifers in the Minami-Kanto gas field, Japan. The cells were non-motile, irregular cocci, 0.7-1.0 µm diameter and occurred singly, pairs or as small aggregates. grew with tri- dimethylamine but not H2/CO2, formate, acetate, methanol dimethyl sulphide. Vitamins, sodium magnesium required for growth. Optimal growth at pH 7.0-7.5, 35...

Little is known about the microbial distribution patterns in subseafloor sediments. This study examines diversity and activities sediments of Nankai Trough, where biogenic gas hydrates are deposited. Illumina sequencing 16S rRNA genes revealed that prokaryotic community structure correlated with hydrate occurrence depth but not sedimentary facies. The bacterial phyla 'Atribacteria' lineage JS1 Chloroflexi dominated all samples, whereas lower taxonomic units accounted for variation related to...

Abstract The Minami-Kanto gas field, where gases are dissolved in formation water, is a potential analogue for marine hydrate area because both areas characterized by the accumulation of microbial methane turbidite sand layers interbedded with mud layers. This study examined physicochemical impacts associated natural production and well drilling on methanogenic activity composition this field. Twenty-four gas-associated water samples were collected from confined aquifers through wells....

Gas hydrates and associated high methane concentrations are widely distributed along the boundary of Nankai Trough off Japan. Radiotracer activity measurements were conducted to estimate current production rates in sediment cores at two sites eastern Tokai containing gas hydrates. Low methanogenesis from CO2 reduction acetate fermentation detected within hydrate-stability zone below Bottom Simulating Reflector (BSR), but not sediments shallow depths (<100 mbsf). The much higher than those...

Fluid sources and flow rates at methane seeps control gas hydrate formation, are potentially archived in authigenic carbonates. Lithium (Li) seeping fluids exhibits a broad range of isotopic fractionation during its ascent to the seafloor, providing information on temperatures fluids. To test applicability Li isotopes as fluid tracer carbonates, this study investigates element isotope composition methane-seep carbonates collected from Black Sea Japan Sea. The Li/Ca ratios δ7Li values...

To determine whether integrons are present in a submarine gas hydrate community, metagenomic DNA was extracted from gas-hydrate-bearing core, 150 m below the seafloor, Cascadian Margin. Integrons and gene cassettes were recovered by PCR sequenced. Thirty-seven integron integrase phylotypes identified. The diverse included members with homology to integrases Methylomonas methanica, Desulfuromonas acetoxidans, Thermodesulfatator indicus, marine uncultured bacteria. cassette composition, 153...