Consulta: creatorFacets:"Parkes, R. John"
Registros recuperados: 7
Data/hora: 09/06/2024 12:36:55

Survival of Desulfotomaculum spores from estuarine sediments after serial autoclaving and high-temperature exposure
Provedor de dados: 5
Autores: O'Sullivan, Louise A.; Roussel, Erwan; Weightman, Andrew J.; Webster, Gordon; Hubert, Casey R. J.; Bell, Emma; Head, Ian; Sass, Henrik; Parkes, R. John.
Bacterial spores are widespread in marine sediments, including those of thermophilic, sulphate-reducing bacteria, which have a high minimum growth temperature making it unlikely that they grow in situ. These Desulfotomaculum spp. are thought to be from hot environments and are distributed by ocean currents. Their cells and spores upper temperature limit for survival is unknown, as is whether they can survive repeated high-temperature exposure that might occur in hydrothermal systems. This was investigated by incubating estuarine sediments significantly above (40–80 °C) maximum in situ temperatures (~23 °C), and with and without prior triple autoclaving. Sulphate reduction occurred at 40–60 °C and at 60 °C was unaffected by autoclaving. Desulfotomaculum sp....
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00216/32759/31181.pdf

Methanogenic diversity and activity in hypersaline sediments of the centre of the Napoli mud volcano, Eastern Mediterranean Sea
Provedor de dados: 5
Autores: Lazar, Cassandre Sara; Parkes, R. John; Cragg, Barry A.; L Haridon, Stephane; Toffin, Laurent.
Submarine mud volcanoes are a significant source of methane to the atmosphere. The Napoli mud volcano, situated in the brine-impacted Olimpi Area of the Eastern Mediterranean Sea, emits mainly biogenic methane particularly at the centre of the mud volcano. Temperature gradients support the suggestion that Napoli is a cold mud volcano with moderate fluid flow rates. Biogeochemical and molecular genetic analyses were carried out to assess the methanogenic activity rates, pathways and diversity in the hypersaline sediments of the centre of the Napoli mud volcano. Methylotrophic methanogenesis was the only significant methanogenic pathway in the shallow sediments (0-40 cm) but was also measured throughout the sediment core, confirming that methylotrophic...
Tipo: Text
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00043/15426/18003.pdf

Complex coupled metabolic and prokaryotic community responses to increasing temperatures in anaerobic marine sediments: critical temperatures and substrate changes
Provedor de dados: 5
Autores: Roussel, Erwan; Cragg, Barry A.; Webster, Gordon; Sass, Henrik; Tang, Xiaohong; Williams, Angharad S.; Gorra, Roberta; Weightman, Andrew J.; Parkes, R. John.
The impact of temperature (0 - 80°C) on anaerobic biogeochemical processes and prokaryotic communities in marine sediments (tidal flat) was investigated in slurries for up to 100 days. Temperature had a non-linear effect on biogeochemistry and prokaryotes with rapid changes over small temperature intervals. Some activities (e.g. methanogenesis) had multiple “windows” within a large temperature range (~10 - 80°C). Others, including acetate oxidation, had maximum activities within a temperature zone, which varied with electron acceptor (metal oxide [up to ~34°C] and sulphate [up to ~50°C]). Substrates for sulphate reduction changed from predominantly acetate below, and H2 above, a 43°C critical temperature; along with changes in activation energies and types...
Tipo: Text
Palavras-chave: Sediment; Temperature; Anaerobic processes; Chemoorganotrophic; Chemolithotrophic; Mineralisation; Sulphate reduction; Methanogenesis; Acetogenesis.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00273/38464/36883.pdf

Glycine betaine as a direct substrate for methanogens (Methanococcoides spp.)
Provedor de dados: 5
Autores: Watkins, Andrew J.; Roussel, Erwan; Parkes, R. John; Sass, Henrik.
Nine marine methanogenic Methanococcoides strains, including the type strains of M. methylutens, M. burtonii and M. alaskense, were tested for the utilization of N-methylated glycines. Three strains (NM1, PM2 and MKM1) used glycine betaine (N,N,N-trimethylglycine) as a substrate for methanogenesis, partially demethylating it to N,N-dimethylglycine, whereas none of the strains used N,N-dimethylglycine or sarcosine (N-methylglycine). Growth rates and growth yields per mol of substrate with glycine betaine (3.96 g dw per mol) were similar to those with trimethylamine (4.11 g dw per mol). However, as glycine betaine is only partially demethylated, the yield per methyl group was significantly higher than with trimethylamine. If glycine betaine and...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00161/27235/25443.pdf

Methanogenic activity and diversity in the centre of the Amsterdam Mud Volcano, Eastern Mediterranean Sea
Provedor de dados: 5
Autores: Lazar, Cassandre; Parkes, R. John; Cragg, Barry A.; L'Haridon, Stephane; Toffin, Laurent.
Marine mud volcanoes are geological structures emitting large amounts of methane from their active centres. The Amsterdam mud volcano (AMV), located in the Anaximander Mountains south of Turkey, is characterized by intense active methane seepage produced in part by methanogens. To date, information about the diversity or the metabolic pathways used by the methanogens in active centres of marine mud volcanoes is limited. 14C-radiotracer measurements showed that methylamines/methanol, H2/CO2 and acetate were used for methanogenesis in the AMV. Methylotrophic methanogenesis was measured all along the sediment core, Methanosarcinales affiliated sequences were detected using archaeal 16S PCR-DGGE and mcrA gene libraries, and enrichments of methanogens showed...
Tipo: Text
Palavras-chave: Methanogenesis; McrA; Archaea.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00087/19795/17538.pdf

Evidence of active methanogen communities in shallow sediments of the Sonora Margin cold seeps
Provedor de dados: 5
Autores: Vigneron, Adrien; L Haridon, Stephane; Godfroy, Anne; Roussel, Erwan; Cragg, Barry A.; Parkes, R. John; Toffin, Laurent.
In the Sonora Margin cold seep ecosystems (Gulf of California), sediments underlying microbial mats harbor high biogenic methane concentrations, fueling various microbial communities, such as abundant lineages of anaerobic methanotrophs (ANME). However, the biodiversity, distribution, and metabolism of the microorganisms producing this methane remain poorly understood. In this study, measurements of methanogenesis using radiolabeled dimethylamine, bicarbonate, and acetate showed that biogenic methane production in these sediments was mainly dominated by methylotrophic methanogenesis, while the proportion of autotrophic methanogenesis increased with depth. Congruently, methane production and methanogenic Archaea were detected in culture enrichments amended...
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00256/36737/35338.pdf

A review of prokaryotic populations and processes in sub-seafloor sediments, including biosphere:geosphere interactions
Provedor de dados: 5
Autores: Parkes, R. John; Cragg, Barry; Roussel, Erwan; Webster, Gordon; Weightman, Andrew; Sass, Henrik.
A general review of the sub-seafloor biosphere is presented. This includes an update and assessment of prokaryotic cell distributions within marine sediments, current deepest 1922 m, and the impact of this on global sub-seafloor biomass estimates. These global estimates appear relatively robust to different calculation approaches and our updated estimate is 5.39 × 1029 cells, taking into consideration new data from very low organic matter South Pacific Gyre sediments. This is higher than other recent estimates, which is justified as several sediments, such as gas hydrate deposits and oil reservoirs, can have elevated cell concentrations. The proposed relationship between elevated cell concentrations and Milankovitch Cycles in sequential diatom rich layers...
Tipo: Text
Palavras-chave: Sub-seafloor biosphere; Marine microbiology; Prokaryotic diversity; Dark energy; Biosphere:geosphere interactions.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00178/28965/27711.pdf