A5072506901- Paleontology and Stratigraphy of Fossils
- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Groundwater and Isotope Geochemistry
- Microbial Community Ecology and Physiology
- Hydrocarbon exploration and reservoir analysis
- Isotope Analysis in Ecology
- Geochemistry and Elemental Analysis
- Mine drainage and remediation techniques
- Marine Biology and Ecology Research
- Microbial Metabolic Engineering and Bioproduction
- Metabolomics and Mass Spectrometry Studies
- Geological and Geochemical Analysis
- Metabolism and Genetic Disorders
- Marine Bivalve and Aquaculture Studies
- Photosynthetic Processes and Mechanisms
- Marine and environmental studies
- Nitrogen and Sulfur Effects on Brassica
- Marine and coastal ecosystems
- Geological and Geophysical Studies
- Genomics and Phylogenetic Studies
- Plant Water Relations and Carbon Dynamics
- Wastewater Treatment and Nitrogen Removal
- Protist diversity and phylogeny
- Origins and Evolution of Life
Washington University in St. Louis
2015-2024
Cooperative Institute for Research in Environmental Sciences
2022
University of Colorado Boulder
2022
British Antarctic Survey
2022
Harvard University
2008-2017
Massachusetts Institute of Technology
2006-2013
Harvard University Press
2009
Planetary Science Institute
2006
Moscow Institute of Thermal Technology
2006
ETH Zurich
2005
The serpentinite-hosted Lost City hydrothermal field is a remarkable submarine ecosystem in which geological, chemical, and biological processes are intimately interlinked. Reactions between seawater upper mantle peridotite produce methane- hydrogen-rich fluids, with temperatures ranging from <40 degrees to 90 C at pH 9 11, carbonate chimneys 30 60 meters tall. A low diversity of microorganisms related methane-cycling Archaea thrive the warm porous interiors edifices. Macrofaunal communities...
The sulfur biogeochemical cycle integrates the metabolic activity of multiple microbial pathways (e.g., sulfate reduction, disproportionation, and sulfide oxidation) along with abiotic reactions geological processes that through various reservoirs. impacts global carbon climate primarily remineralization organic carbon. Over timescales, cycling is closely tied to redox state Earth's exosphere burial oxidized (sulfate) reduced (sulfide) species in marine sediments. Biological associated...
There is a close connection between modern-day biosynthesis of particular triterpenoid biomarkers and presence molecular oxygen in the environment. Thus, detection steroid hydrocarbons far back Earth history has been used to infer antiquity oxygenic photosynthesis. This prompts question: were these compounds produced similarly past? In this paper, we address question with review current state knowledge surrounding requirement for phylogenetic patterns distribution biosynthetic pathways. The...
Phanerozoic levels of atmospheric oxygen relate to the burial histories organic carbon and pyrite sulfur. The sulfur cycle remains poorly constrained, however, leading concomitant uncertainties in O 2 budgets. Here we present experiments linking magnitude fractionations multiple isotopes rate microbial sulfate reduction. data demonstrate that such are controlled by availability electron donor (organic matter), rather than concentration acceptor (sulfate), an environmental constraint varies...
Significance The function of the cell membrane as a barrier and matrix for biochemical activity relies on properties imparted by lipids. In eukaryotes, sterols are crucial modulating molecular order membranes. Sterol ordering provides basis lateral segregation promotes fluid, mechanically robust plasma membrane. How do organisms that lack determine order? Hopanoids bacterial lipids have been demonstrated to sterol-like in vitro. We now explore distribution hopanoids their effect membranes...
Proteorhodopsins (PRs) are retinal-containing proteins that catalyze light-activated proton efflux across the cell membrane. These photoproteins known to be globally distributed in ocean's photic zone, and they found a diverse array of Bacteria Archaea. Recently, light-enhanced growth rates yields have been reported at least one PR-containing marine bacterium, but physiological basis stimulation has not yet determined. To describe more fully PR photosystem genetics biochemistry, we...
Studies of microbial sulfate reduction have suggested that the magnitude sulfur isotope fractionation varies with concentration. Small apparent fractionations preserved in Archean rocks been interpreted as suggesting concentrations <200 μm, while larger thereafter to require higher concentrations. In this work, we demonstrate imposed by can be a function concentration over millimolar range, but nature relationship depends on organism studied. Two sulfate-reducing bacteria grown continuous...
Sulfur isotopes in the geological record integrate a combination of biological and diagenetic influences, but key control on ratio sulfur sedimentary materials is magnitude isotope fractionation imparted during dissimilatory sulfate reduction. This controlled by flux through network chemical reactions involved reduction effect associated with each these reactions. Despite its importance, constituting not fully understood, two principle networks underpinning most models. In this study, we...
Ocean Anoxic Event 2 (OAE2) was a period of dramatic disruption to the global carbon cycle when massive amounts organic matter (OM) were buried in marine sediments via complex and controversial mechanisms. Here we investigate role OM sulfurization, which makes less available for microbial respiration, driving variable preservation OAE2 sedimentary strata from Pont d'Issole (France). We find correlations between concentration, S:C ratio, S-isotope composition, sulfur speciation suggesting...
Here we give names to three new species of Paraburkholderia that can remain in symbiosis indefinitely the spores a soil dwelling eukaryote, Dictyostelium discoideum. The P. agricolaris sp. nov., hayleyella and bonniea nov. are widespread across eastern USA were isolated as internal symbionts wild-collected D. We describe these using several approaches. Evidence they each distinct comes from their phylogenetic position, average nucleotide identity, genome-genome distance, carbon usage,...
The precise interpretation of environmental sulfur isotope records requires a quantitative understanding the biochemical controls on fractionation by principle isotope-fractionating process within S cycle, microbial sulfate reduction (MSR). Here we provide only direct observation major (34S/32S) and minor (33S/32S, 36S/32S) fractionations imparted central enzyme in energy metabolism reducers, dissimilatory sulfite reductase (DsrAB). Results from vitro experiments allow us to calculate DsrAB...
Abundant tubular macrofossils occur in finely laminated siltstones and shales of the 548–542 Ma Schwarzrand Subgroup, Nama Group, Namibia. The tubes both Vingerbreek Feldschuhhorn members commonly dense populations always fine-grained, lower shore-face lithologies deposited below fair-weather wave base. are preserved mostly as compressed casts molds that range width from 0.6 to 2.1 mm; apparently incomplete specimens reach lengths up 10 cm. All show sinuous bending occasional brittle...
Detailed analysis of 16S rRNA and intact polar lipids (IPLs) from streamer biofilm communities (SBCs), collected geochemically similar hot springs in the Lower Geyser Basin, Yellowstone National Park, shows good agreement affirm that IPLs can be used as reliable markers for microbial constituents SBCs. Uncultured Crenarchaea are prominent SBS, their contain both glycosidic mixed glyco-phospho head groups with tetraether cores, having 0-4 rings. Archaeal IPL contributions increase increasing...
Previous studies of the stoichiometry thiosulfate oxidation by colorless sulfur bacteria have failed to demonstrate mass balance sulfur, indicating that unidentified oxidized products must be present. Here reaction and kinetics under variable pH conditions during growth Thiomicrospira thermophila strain EPR85, isolated from diffuse hydrothermal fluids at East Pacific Rise, is presented. At 8.0, was stoichiometrically converted sulfate. lower pH, were extracellular elemental We able replicate...