Evidence for only minor contributions from bacteria to sedimentary organic carbon

Because their molecular signatures are often prominent in extracts of sediments, bacteria are thought to be important contributors to petroleum source beds. It has been shown recently, however, that abundances of biomarkers do not always reflect relative contributions to sedimentary organic carbon (...

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Bibliographic Details
Published in:Nature (London) 1994-05, Vol.369 (6477), p.224-227
Main Authors: Hartgers, W. A., Sinninghe Damste, J. S., Requejo, A. G., Allan, J., Hayes, J. M., de Leeuw, J. W.
Format: Article
Language:English
Subjects:
Bacteria
Canada
Carbon
Carbon - chemistry
Carbon - metabolism
Carbon Isotopes
Carotenoids
Carotenoids - analysis
Chlorobi - metabolism
Chlorophyta
Earth sciences
Earth, ocean, space
Environmental Microbiology
Exact sciences and technology
Exobiology
Geologic Sediments - analysis
Geologic Sediments - chemistry
Geologic Sediments - microbiology
Hydrocarbons
Hydrocarbons - analysis
Isotope geochemistry
Isotope geochemistry. Geochronology
Marine
Organic carbon
Organic chemistry
Petroleum - analysis
Petroleum - microbiology
Photosynthesis
Sedimentary rocks
Sediments
Space life sciences
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Summary:Because their molecular signatures are often prominent in extracts of sediments, bacteria are thought to be important contributors to petroleum source beds. It has been shown recently, however, that abundances of biomarkers do not always reflect relative contributions to sedimentary organic carbon (Corg). The contribution of photosynthetic green sulphur bacteria to sediments can be assessed effectively because the diagenetic products of distinctive carotenoids from these organisms occur widely and their biomass is isotopically labelled, being enriched in 13C. We show here that, although sediments and oils from the Western Canada and Williston basins contain prominent biomarkers of photosynthetic bacteria, the absence of 13C enrichment in the total Corg requires that the bacterial contribution is in fact minimal. Although the importance of bacterial reworking of sedimentary debris cannot be doubted, we argue that our findings, when considered in conjunction with those from other settings, suggest that bacterial biomass may commonly represent only a minor component of total Corg in carbonaceous rocks.
ISSN:0028-0836
1476-4687
DOI:10.1038/369224a0