The proposed project is an investigation of a newly discovered consortium comprising a novel group of SM1- Archaea and bacterium, mainly Thiothrix, that takes on the appearance of a string-of-pearls.
Objects bearing a close physical resemblance to these consortia have been found in rocks as old a 1500 million years and are presently considered 'problematic' fossils because there have been no known modern analogues for comparative study. In this project we will investigate the physiology and metabolism of the string-of-peals by investigating changes in their lipid biomarker compositions in response to exposure to different nutrients.
Our primary objective will be to follow the flow and fate of carbon through the consortium by feeding substrates labelled with s table isotope (13C) applied during growth in the natural environment. We expect the results will show the preferred carbon sources of the bacteria, as well as on the intra-consortium carbon transfer.
Furthermore, predictions on metabolic activity and growth rates are expected. The uptake of label into both organisms will be followed by analyses of extractable lipid biomarkers and other metabolic intermediates using gas chromatography-isotopic resolution mass spectrometry (GC-c-IRMS).
We will be able to determine the direction of carbon flow by establishing which compounds are labelled first and because bacterial and archaeal lipids are readily distinguished on the basis of their chemical structures and because some preliminary analyses of the lipid contents.
If other, presently unknown, lipid biomarkers are found, their structures will be investigated using high resolution mass spectrometry and high pressure liquid chromatography mass spectrometry. This aspect will add to the knowledge base about lipid biomarker-organism associations.
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