| lipids as biogeochemical proxies |
In support of our research on ancient sediments, it is essential to know the metabolic capabilities of geologically significant microorganisms as they relate to biosynthesis of diagnostic lipids such as hopanoids, steroids and other isoprene-based lipids. Sub-projects within this larger umbrella are:
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bio- and geo-hopanoids as tracers of cyanobacterial productivity and nitrogen fixation in the ocean
This project will develop lipid biomarker proxies that will assist the study of marine cyanobacteria in both the modern ocean and in the geological record. We are testing the hypothesis that cyanobacteria are a dominant source of distinctive lipids known as bacteriohopanepolyols (BHPs) produced in the marine water column and likely to be recorded in underlying sediments. If proven, it will provide a sound basis for attributing a specific biological origin to some of the hopane hydrocarbons that occur abundantly in ancient sediments and petroleum.
support: National Science Foundation
publications:
Talbot H.M., Summons R.E., Jahnke L.L. and Farrimond P. (2003) Characteristic fragmentation of bacteriohopanepolyols during atmospheric pressure chemical ionisation liquid chromatography/ion trap mass spectrometry. Rapid Communications in Mass Spectrometry 17: 1-9. |
chlorogloeopsis. image courtesy of L.L. Jahnke
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lipids of hyperthermophilic Archaea
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deep ocean hydrothermal vent. photo courtesy of National Geographic |
This project is conducted as an adjunct to our work in hydrothermal ecosystems where lipid proxies are a means to understand community composition and metabolism. Key groups, for which we are attempting to ascribe diagnostic lipid patterns, include the thermophilic methanogens and the Ignicoccus-Nanoarchaeum consortium. Meshed with this work, Kai-Uwe Hinrichs (University of Bremen) and Helen Sturt (Woods Hole) are investigating LC-MS (liquid chromatography mass spectrometry) as a tool for studying the intact lipid distributions of a wide variety of cultured microorganisms in order to be able to detect their presence and metabolism in the Deep Subsurface Biosphere. |
support: NASA and MIT
publications:
Summons R.E., Embaye T., Jahnke L.L. and Baumgartner M. (2002) New Ether Lipid Biomarkers from a Hyperthermophilic Methanogen. Abstracts with Program, 12th Annual VM Goldschmidt Conference, Davos Switzerland Geochim. Cosmochim. Acta 66, A752.
Sturt H.F., Smith K.J., Teske A., Jahnke L.L., Summons R.E. and Hinrichs K.-U. (2003). Structural Analysis of Intact Polar Lipids from Extremophiles. Abstracts with Program, International Meeting on Organic Geochemistry, Krakov, Poland.
Jahn U., Summons R., Sturt H., Grosjean E. and Huber H., 2004. Composition and source of the lipids of Nanoarchaeum equitans and their origin in the cytoplasmic membrane of its host Ignicoccus sp. KIN4/I. Archives of Microbiology, Submitted. |
