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Open Access. Powered by Scholars. Published by Universities.®

2006

Selected Works

Karen Lloyd

Articles 1 - 3 of 3

Full-Text Articles in Life Sciences

An Anaerobic Methane Oxidizing Community Of Anme-1b Archaea In Hypersaline Gulf Of Mexico Sediments, Karen Lloyd, Laura Lapham, Andreas Teske Oct 2006

An Anaerobic Methane Oxidizing Community Of Anme-1b Archaea In Hypersaline Gulf Of Mexico Sediments, Karen Lloyd, Laura Lapham, Andreas Teske

Karen Lloyd

Sediments overlying a brine pool methane seep in the Gulf of Mexico (Green Canyon 205) were analyzed using molecular and geochemical approaches to identify geochemical controls on microbial community composition and stratification. 16S rRNA gene and rRNA clone libraries, as well as mcrA gene clone libraries, showed that the archaeal community consists predominantly of ANME-1b methane oxidizers; no archaea of other ANME subgroups were found with general and group-specific PCR primers. The ANME-1b community was found in the sulfate-methane interface, where undersaturated methane concentrations of ca. 100 to 250 _M coexist with sulfate concentrations around 10 mM. Clone libraries of ...


Survival And Growth Of Two Heterotrophic Hydrothermal Vent Archaea, Pyrococcus Strain Gb-D And Thermococcus Fumicolans, Under Low Ph And High Sulfide Concentrations In Combination With High Temperature And Pressure Regimes, Virginia Edgcomb, Stephen Molyneaux, Simone Böer, Carl Wirsen, Mark Saito, Michael Atkins, Karen Lloyd, Andreas Teske Dec 2005

Survival And Growth Of Two Heterotrophic Hydrothermal Vent Archaea, Pyrococcus Strain Gb-D And Thermococcus Fumicolans, Under Low Ph And High Sulfide Concentrations In Combination With High Temperature And Pressure Regimes, Virginia Edgcomb, Stephen Molyneaux, Simone Böer, Carl Wirsen, Mark Saito, Michael Atkins, Karen Lloyd, Andreas Teske

Karen Lloyd

Growth and survival of hyperthermophilic archaea in their extreme hydrothermal vent and subsurface environments are controlled by chemical and physical key parameters. This study examined the effects of elevated sulfide concentrations, temperature, and acidic pH on growth and survival of two hydrothermal vent archaea (Pyrococcus strain GB-D and Thermococcus fumicolans) under high temperature and pressure regimes. These two strains are members of the Thermococcales, a family of hyperthermophilic, heterotrophic, sulfur-reducing archaea that occur in high densities at vent sites. As actively growing cells, these two strains tolerated regimes of pH, pressure, and temperature that were in most cases not tolerated ...


Heterotrophic Archaea Dominate Sedimentary Subsurface Ecosystems Off Peru, Jennifer Biddle, Julius Lipp, Karen Lloyd, Ketil Sørensen, Rika Anderson, Helen Fredericks, Marcus Elvert, Timothy Kelly, Daniel Schrag, Mitchell Sogin, Jean Brenchley, Andreas Teske, Christopher House, Kaw-Uwe Hinrichs Dec 2005

Heterotrophic Archaea Dominate Sedimentary Subsurface Ecosystems Off Peru, Jennifer Biddle, Julius Lipp, Karen Lloyd, Ketil Sørensen, Rika Anderson, Helen Fredericks, Marcus Elvert, Timothy Kelly, Daniel Schrag, Mitchell Sogin, Jean Brenchley, Andreas Teske, Christopher House, Kaw-Uwe Hinrichs

Karen Lloyd

Studies of deeply buried, sedimentary microbial communities and associated biogeochemical processes during Ocean Drilling Program Leg 201 showed elevated prokaryotic cell numbers in sediment layers where methane is consumed anaerobically at the expense of sulfate. Here, we show that extractable archaeal rRNA, selecting only for active community members in these ecosystems, is dominated by sequences of uncultivated Archaea affiliated with the Marine Benthic Group B and the Miscellaneous Crenarchaeotal Group, whereas known methanotrophic Archaea are not detectable. Carbon flow reconstructions based on stable isotopic compositions of whole archaeal cells, intact archaeal membrane lipids, and other sedimentary carbon pools indicate that ...