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| Titel |
Novel biohopanoid molecular proxies for bacterial populations and processes |
| VerfasserIn |
Helen Talbot, Martin Cooke, Chun Zhu, Luke Handley, Jung-Hyun Kim, Richard Pancost, Thomas Wagner |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048383
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| Zusammenfassung |
| Microbially-mediated processes at the Earth’s surface and in the subsurface are fundamental controls on the global carbon and climate cycle. Bacteria and other microorganisms produce a variety of lipid biomarkers which are important for studying their activity in modern and Recent environments; however, many of these molecules (e.g. fatty acids) are not well preserved in the sedimentary record.
An alternative approach to tackle bacterial biomarkers is to apply bacteriohopanepolyols (BHPs)[1], membrane lipids biosynthesised by many, but not all bacteria, which have recently been identified in sediment samples up to 55 Ma. These compounds, consisting of a stable pentacyclic hydrocarbon skeleton with an extended, highly functionalised side chain containing at least 4 functional groups, are significant components in soils and sediments, both terrestrial and marine.
Although some BHPs have a diverse range of biological source organisms, others have more restricted origins and recently several BHPs have been proposed as novel markers for specific biogeochemical processes including aerobic methane oxidation [2] and nitrogen-fixation [3,4]. Additionally, the persistent need to understand carbon dynamics and reactions involving organic matter at the land-ocean interface has lead to a tentatively proposed new BHP based approach. We identified a group of compounds related to adenosylhopane [1] which are abundant components in soils but generally scarce or absent in lacustrine sediments and open marine systems [5]. We subsequently proposed that the relative contribution of this group of compounds to the sedimentary BHP pool may be a useful proxy for terrestrial organic matter input [6], although further development is still ongoing. As a foundation to this potential application, we have surveyed the BHP composition of over 600 soil samples from around the world and will here present a synthesis of this data, comparing terrestrial BHP fingerprints to those from a range of aquatic sediments of different ages, including new data from a large scale study of the Yangtze River-East China Sea surface sediment transect.
These novel applications will be contextualised within a summary of current knowledge of relevant source organisms and environmental factors affecting BHP biosynthesis as well as a consideration of knowledge of the fate of these molecules in the marine systems. Finally we will highlight some of the major outstanding questions currently driving this growing research area.
References
[1] Talbot & Farrimond (2007) Org. Geochem 38, 1212-1225.
[2] Coolen et al. (2008) Env. Microbiol 10, 1783-1803.
[3] Handley et al. (2010) Org. Geochem. 41, 910-914.
[4] Kim et al. (2011) G3 in press.
[5] Cooke et al. (2008) Org. Geochem. 39, 1347-1350.
[6] Cooke et al. (2008) Org. Geochem. 39, 958-971. |
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