ORCID Profile
0000-0002-2898-3374
Current Organisation
Princeton University
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Publisher: American Society for Microbiology
Date: 12-2005
DOI: 10.1128/AEM.71.12.8773-8783.2005
Abstract: Alkaline, sulfidic, 54 to 60°C, 4 to 53 million-year-old meteoric water emanating from a borehole intersecting quartzite-hosted fractures .3 km beneath the surface supported a microbial community dominated by a bacterial species affiliated with Desulfotomaculum spp. and an archaeal species related to Methanobacterium spp. The geochemical homogeneity over the 650-m length of the borehole, the lack of iding cells, and the absence of these microorganisms in mine service water support an indigenous origin for the microbial community. The coexistence of these two microorganisms is consistent with a limiting flux of inorganic carbon and SO 4 2− in the presence of high pH, high concentrations of H 2 and CH 4 , and minimal free energy for autotrophic methanogenesis. Sulfide isotopic compositions were highly enriched, consistent with microbial SO 4 2− reduction under hydrologic isolation. An analogous microbial couple and similar abiogenic gas chemistry have been reported recently for hydrothermal carbonate vents of the Lost City near the Mid-Atlantic Ridge (D. S. Kelly et al., Science 307: 1428-1434, 2005), suggesting that these features may be common to deep subsurface habitats (continental and marine) bearing this geochemical signature. The geochemical setting and microbial communities described here are notably different from microbial ecosystems reported for shallower continental subsurface environments.
Publisher: Wiley
Date: 18-11-2008
DOI: 10.1111/J.1472-4669.2008.00174.X
Abstract: A novel, anaerobically grown microbial biofilm, scraped from the inner surface of a borehole, 1474 m below land surface within a South African, Witwatersrand gold mine, contains framboidal pyrite. Water flowing from the borehole had a temperature of 30.9 degrees C, a pH of 7.4, and an Eh of -50 mV. Examination of the biofilm using X-ray diffraction, field emission gun scanning electron microscope equipped for energy dispersive X-ray microanalysis demonstrated that the framboids formed within a matrix of bacteria and biopolymers. Focused ion beam sectioning of framboids followed by NEXAFS measurements using both scanning transmission X-ray microscopy and X-ray photoelectron emission microscopy revealed that the pyrite crystals grew within an organic carbon matrix consisting of exopolysaccharides and possibly extracellular DNA, which is intuitively important in sulfide mineral diagenesis. Growth of in idual pyrite crystals within the framboid occurred inside organic templates confirms the association between framboidal pyrite and organic materials in low-temperature diagenetic environments and the important role of microenvironments in biofilms in regulating geochemical cycles.
Publisher: Informa UK Limited
Date: 11-2003
DOI: 10.1080/713851170
Publisher: American Association for the Advancement of Science (AAAS)
Date: 10-10-2008
Abstract: DNA from low-bio ersity fracture water collected at 2.8-kilometer depth in a South African gold mine was sequenced and assembled into a single, complete genome. This bacterium, Candidatus Desulforudis audaxviator , composes .9% of the microorganisms inhabiting the fluid phase of this particular fracture. Its genome indicates a motile, sporulating, sulfate-reducing, chemoautotrophic thermophile that can fix its own nitrogen and carbon by using machinery shared with archaea. Candidatus Desulforudis audaxviator is capable of an independent life-style well suited to long-term isolation from the photosphere deep within Earth's crust and offers an ex le of a natural ecosystem that appears to have its biological component entirely encoded within a single genome.
Publisher: Wiley
Date: 22-05-2008
DOI: 10.1111/J.1472-4669.2008.00163.X
Abstract: We study structure and function. Credit of course, goes to TJB, for it is from him that I inherited the habit of personifying bacteria and attempting to think like a bacterium, to better understand what they do. This work has taken us to wonderful places such as Yellowstone National Park, The Canadian Arctic, Australia, and the deep subsurface in the Republic of South Africa, the subject of this manuscript. From their perspective, why they do what they do is simple, to live. How they do it, is more challenging for us to understand, so it is something that we continue to work on. The marvel of bacteria is something that I, in turn, try to pass on to my students where I hope it will find fertile ground and provide as much enjoyment as it has given me - G. Southam. A biofilm (mine-slime) collected from the Northam Platinum mine in the Republic of South Africa contained a new bacterial morphotype. Mine-slimes are generally considered to be microbiologically compromised, subsurface s les due to the likelihood of contamination from the mining environment. However, careful examination of this biofilm demonstrated that it possessed a erse bacterial population that included organisms that are consistent with the deep subsurface, suggesting that mine-slimes represent an underutilized, 'natural' bacterial enrichment. Using scanning and transmission electron microscopy, a novel, branching, filamentous, star-shape bacterium (in cross section) has been found, adding a new bacterial morphotype and strategy that bacteria have demonstrated to increase their surface area to volume ratio.
Publisher: Springer Science and Business Media LLC
Date: 09-11-2020
DOI: 10.1038/S41587-020-0718-6
Abstract: The reconstruction of bacterial and archaeal genomes from shotgun metagenomes has enabled insights into the ecology and evolution of environmental and host-associated microbiomes. Here we applied this approach to ,000 metagenomes collected from erse habitats covering all of Earth’s continents and oceans, including metagenomes from human and animal hosts, engineered environments, and natural and agricultural soils, to capture extant microbial, metabolic and functional potential. This comprehensive catalog includes 52,515 metagenome-assembled genomes representing 12,556 novel candidate species-level operational taxonomic units spanning 135 phyla. The catalog expands the known phylogenetic ersity of bacteria and archaea by 44% and is broadly available for streamlined comparative analyses, interactive exploration, metabolic modeling and bulk download. We demonstrate the utility of this collection for understanding secondary-metabolite biosynthetic potential and for resolving thousands of new host linkages to uncultivated viruses. This resource underscores the value of genome-centric approaches for revealing genomic properties of uncultivated microorganisms that affect ecosystem processes.
Publisher: Elsevier BV
Date: 03-2007
DOI: 10.1016/J.SYAPM.2006.04.003
Abstract: A thermophilic facultative bacterial isolate was recovered from 3.2km depth in a gold mine in South Africa. This isolate, designated GE-7, was cultivated from pH 8.0, 50 degrees C water from a dripping fracture near the top of an exploration tunnel. GE-7 grows optimally at 65 degrees C and pH 6.5 on a wide range of carbon substrates including cellobiose, hydrocarbons and lactate. In addition to O(2), GE-7 also utilizes nitrate as an electron acceptor. GE-7 is a long rod-shaped bacterium (4-6microm longx0.5microm wide) with terminal endospores and flagella. Phylogenetic analysis of GE-7 16S rDNA sequence revealed high sequence similarity with G. thermoleovorans DSM 5366(T) (99.6%), however, certain phenotypic characteristics of GE-7 were distinct from this and other previously described strains of G. thermoleovorans.
Publisher: Informa UK Limited
Date: 09-2006
Publisher: Elsevier BV
Date: 02-2021
Publisher: Informa UK Limited
Date: 09-2006
Publisher: Elsevier BV
Date: 03-1991
Publisher: Informa UK Limited
Date: 26-09-2007
Publisher: American Society for Microbiology
Date: 09-2009
DOI: 10.1128/AEM.02948-08
Abstract: Values of Δ 34 S ( \\batchmode \\documentclass[fleqn,10pt,legalpaper]{article} \\usepackage{amssymb} \\usepackage{amsfonts} \\usepackage{amsmath} \\pagestyle{empty} \\begin{document} \\({=}{\\delta}^{34}S_{HS}{-}{\\delta}^{34}S_{SO_{4}}\\) \\end{document} , where δ 34 S HS and \\batchmode \\documentclass[fleqn,10pt,legalpaper]{article} \\usepackage{amssymb} \\usepackage{amsfonts} \\usepackage{amsmath} \\pagestyle{empty} \\begin{document} \\({\\delta}^{34}S_{SO_{4}}\\) \\end{document} indicate the differences in the isotopic compositions of the HS − and SO 4 2− in the eluent, respectively) for many modern marine sediments are in the range of −55 to −75‰, much greater than the −2 to −46‰ ε 34 S (kinetic isotope enrichment) values commonly observed for microbial sulfate reduction in laboratory batch culture and chemostat experiments. It has been proposed that at extremely low sulfate reduction rates under hypersulfidic conditions with a nonlimited supply of sulfate, isotopic enrichment in laboratory culture experiments should increase to the levels recorded in nature. We examined the effect of extremely low sulfate reduction rates and electron donor limitation on S isotope fractionation by culturing a thermophilic, sulfate-reducing bacterium, Desulfotomaculum putei , in a biomass-recycling culture vessel, or “retentostat.” The cell-specific rate of sulfate reduction and the specific growth rate decreased progressively from the exponential phase to the maintenance phase, yielding average maintenance coefficients of 10 −16 to 10 −18 mol of SO 4 cell −1 h −1 toward the end of the experiments. Overall S mass and isotopic balance were conserved during the experiment. The differences in the δ 34 S values of the sulfate and sulfide eluting from the retentostat were significantly larger, attaining a maximum Δ 34 S of −20.9‰, than the −9.7‰ observed during the batch culture experiment, but differences did not attain the values observed in marine sediments.
Publisher: Society of Economic Geologists
Date: 12-1996
Publisher: Wiley
Date: 20-08-2012
DOI: 10.1111/J.1472-4669.2012.00340.X
Abstract: By ~2.9 Ga, the time of the deposition of the Witwatersrand Supergroup, life is believed to have been well established on Earth. Carbon remnants of the microbial biosphere from this time period are evident in sediments from around the world. In the Witwatersrand Supergroup, the carbonaceous material is often concentrated in seams, closely associated with the gold deposits and may have been a mobile phase 2 billion years ago. Whereas today the carbon in the Witwatersrand Supergroup is presumed to be immobile, hollow hydrocarbon spheres ranging in size from 50 μm were discovered emanating from a borehole drilled through the carbon-bearing seams suggesting that a portion of the carbon may still be mobile in the deep subsurface. ToF-SIMS and STXM analyses revealed that these spheres contain a suite of alkane, alkenes, and aromatic compounds consistent with the described organic-rich carbon seams within the Witwatersrand Supergroup's auriferous reef horizons. Analysis by electron microscopy and ToF-SIMS, however, revealed that these spheres, although most likely composed of biogenic carbon and resembling biological organisms, do not retain any true structural, that is, fossil, information and were formed by an abiogenic process.
Location: United States of America
No related grants have been discovered for Tullis Onstott.