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| 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 |
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| 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 |
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| 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 |
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| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00161/27235/25443.pdf |
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| Parkes, Ronald John; Berlendis, Sabrina; Roussel, Erwan; Bahruji, Hasiliza; Webster, Gordon; Oldroyd, Anthony; Weightman, Andrew J.; Bowker, Michael; Davies, Philipp R; Sass, Henrik. |
| Microbial populations exist to great depths on Earth, but with apparently insufficient energy supply. Earthquake rock fracturing produces H2 from mechanochemical water splitting, however, microbial utilization of this widespread potential energy source has not been directly demonstrated. Here, we show experimentally that mechanochemically generated H2 from granite can be directly, long‐term, utilized by a CH4 producing microbial community. This is consistent with CH4 formation in subsurface rock fracturing in the environment. Our results not only support water splitting H2 generation as a potential deep biosphere energy source, but as an oxidant must also be produced, they suggest that there is also a respiratory oxidant supply in the subsurface which is... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00483/59444/62283.pdf |
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| 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 |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00216/32759/31181.pdf |
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