McDermott, Tim R.

Dr. Tim R. McDermott

Associate Professor
Department of Land Resources and Environmental Sciences
Montana State University
Bozeman, MT

Research Overview

Thermophile research in the McDermott laboratory involves two independent research thrusts. One involves the development of a program that seeks to examine, characterize, and understand microbial populations inhabiting geothermally heated soil environments. The discovery, isolation, and characterization of novel and diverse thermophiles is a central platform of this particular project. The second thrust focuses on microbe-arsenic interactions in geothermal environments. Here, we wish to extend our general understanding of microbial arsenic redox biochemistry and physiology, and whether these reactions, when coupled with other relevant aqueous and solid phase chemical signatures, can be used as biomarkers of present or past microbial activity.

Geothermal Soils:

In recent work, we have isolated a novel thermophile, Thermobaculum terrenum, that appears to be the only cultured and characterized representative of a clade (Botero et al. 2004), which was previously comprised entirely of environmental clones within the phylum Chloroflexi (formally the Green Non-Sulfur division). In addition, we have isolated and characterized a proposed novel species of Geobacillus (species name tepidamans) (Schaeffer et al, submitted). In other work, we have employed DNA- and RNA-based molecular techniques to study population shifts occurring in response to increased soil temperature resulting from expansion of underlying geothermal activity (Norris et al. 2002b).

Microbe-Arsenic Interactions.

Work in this thrust seeks to improve our understanding of how microbes interact with and transform arsenic. Initial studies were molecular-based examinations of the microbial communities in arsenite-oxidizing thermal springs (in collaboration with Bill Inskeep). Subsequent work with this spring has involved the cultivation and characterization of different Hydrogenobaculum isolates (Donahoe-Christiansen et al. 2004). These hydrogenobacula are also being studied for their contribution to sulfide and hydrogen oxidation in these springs. This work has provided training for one postdoc, one MS student, and three undergraduate interns.

Other microbe-arsenic interaction work has included a proteomics examination of Sulfolobus global responses to arsenic (Barry et al. In preparation). The goal of this particular study was to extend our knowledge base of microbe-arsenic interactions beyond its current state, which is largely confined to studies that focus on ars gene expression. Other arsenic work includes studies aimed at investigating the potential contribution of cyanidia to arsenic transformations in the Yellowstone thermal springs. These evolutionarily ancient eukaryotic algae are found throughout Yellowstone and often dominate microbial communities in low pH thermal springs, pools, and soils.

  1. Metagenome sequence analysis of filamentous microbial communities obtained from geochemically distinct geothermal channels reveals specialization of three Aquificales lineages
    Frontiers in Microbiology, 2013
  2. Relative Importance of H2 and H2S as Energy Sources for Primary Production in Geothermal Springs
    Applied and Environmental Microbiology, 2008
  3. New Insights into Microbial Oxidation of Antimony and Arsenic
    Applied and Environmental Microbiology, 2007
  4. Geomicrobiology of Acid-Sulfate-Chloride Springs in Yellowstone National Park
    Geothermal Biology and Geochemistry in YNP [TBI Text!], 2005
  5. Poly(A) Polymerase Modification and Reverse Transcriptase PCR Amplification of Environmental RNA
    Applied and Environmental Microbiology, 2005
  6. Observations Concerning Nitrogen Cycling in a Yellowstone Thermal Soil Environment
    Geothermal Biology and Geochemistry in YNP [TBI Text!], 2005
  7. Arsenite-Oxidizing Hydrogenobaculum Strain Isolated from an Acid-Sulfate-Chloride Geothermal Spring in Yellowstone National Park
    Applied and Environmental Microbiology, 2004
  8. Bacterial Populations Associated with the Oxidation and Reduction of Arsenic in an Unsaturated Soil
    Environmental Science & Technology, 2004
  9. Thermobaculum terrenum gen. nov., sp. nov.: a non-phototrophic gram-positive thermophile representing an environmental clone group related to the Chloroflexi (green non-sulfur bacteria) and Thermomicrobia
    Archives of Microbiology, 2004
  10. Classification of isolates from locations in Austria and Yellowstone National Park as Geobacillus tepidamans sp. nov.
    International Journal of Systematic and Evolutionary Microbiology, 2004
  11. Soil Microbial Community Structure across a Thermal Gradient following a Geothermal Heating Event
    Applied and Environmental Microbiology, 2002
  12. The long-term effects of UV exclusion on the microbial composition and photosynthetic competence of bacteria in hot-spring microbial mats
    FEMS Microbiology Ecology, 2002
  13. Molecular analysis of microbial community structure in an arsenite-oxidizing acidic thermal spring
    Environmental Microbiology, 2001
  14. Rapid Oxidation of Arsenite in a Hot Spring Ecosystem, Yellowstone National Park
    Environmental Science & Technology, 2001
  15. Viruses from extreme thermal environments
    Proceedings of the National Academy of Sciences, 2001
  16. Microbial Populations Associated with the Reduction and Enhanced Mobilization of Arsenic in Mine Tailings
    Environmental Science & Technology, 2001