• Publications
  • Influence
Molecular evidence for an active endogenous microbiome beneath glacial ice
Geologic, chemical and isotopic evidence indicate that Earth has experienced numerous intervals of widespread glaciation throughout its history, with roughly 11% of present day Earth’s land surfaceExpand
  • 95
  • 12
Diversity, Abundance, and Potential Activity of Nitrifying and Nitrate-Reducing Microbial Assemblages in a Subglacial Ecosystem †
ABSTRACT Subglacial sediments sampled from beneath Robertson Glacier (RG), Alberta, Canada, were shown to harbor diverse assemblages of potential nitrifiers, nitrate reducers, and diazotrophs, asExpand
  • 109
  • 10
A late methanogen origin for molybdenum-dependent nitrogenase.
Mounting evidence indicates the presence of a near complete biological nitrogen cycle in redox-stratified oceans during the late Archean to early Proterozoic (c. 2.5-2.0 Ga). It has been suggestedExpand
  • 85
  • 9
  • PDF
Chemolithotrophic Primary Production in a Subglacial Ecosystem
ABSTRACT Glacial comminution of bedrock generates fresh mineral surfaces capable of sustaining chemotrophic microbial communities under the dark conditions that pervade subglacial habitats.Expand
  • 70
  • 9
  • PDF
Biological nitrogen fixation in acidic high-temperature geothermal springs in Yellowstone National Park, Wyoming.
The near ubiquitous distribution of nifH genes in sediments sampled from 14 high-temperature (48.0-89.0°C) and acidic (pH 1.90-5.02) geothermal springs in Yellowstone National Park suggested a roleExpand
  • 32
  • 9
  • PDF
Transcriptional profiling of nitrogen fixation in Azotobacter vinelandii.
Most biological nitrogen (N(2)) fixation results from the activity of a molybdenum-dependent nitrogenase, a complex iron-sulfur enzyme found associated with a diversity of bacteria and someExpand
  • 68
  • 8
An Alternative Path for the Evolution of Biological Nitrogen Fixation
Nitrogenase catalyzed nitrogen fixation is the process by which life converts dinitrogen gas into fixed nitrogen in the form of bioavailable ammonia. The most common form of nitrogenase todayExpand
  • 65
  • 7
  • PDF
Environmental Constraints Underpin the Distribution and Phylogenetic Diversity of nifH in the Yellowstone Geothermal Complex
Biological nitrogen fixation is a keystone process in many ecosystems, providing bioavailable forms of fixed nitrogen for members of the community. In the present study, degenerate primers targetingExpand
  • 34
  • 6
  • PDF
[FeFe]-hydrogenase in Yellowstone National Park: evidence for dispersal limitation and phylogenetic niche conservatism
Hydrogen (H2) has an important role in the anaerobic degradation of organic carbon and is the basis for many syntrophic interactions that commonly occur in microbial communities. Little is known,Expand
  • 58
  • 5
  • PDF
Competition for Ammonia Influences the Structure of Chemotrophic Communities in Geothermal Springs
ABSTRACT Source waters sampled from Perpetual Spouter hot spring (pH 7.03, 86.4°C), Yellowstone National Park, WY, have low concentrations of total ammonia, nitrite, and nitrate, suggesting nitrogenExpand
  • 24
  • 4
  • PDF