Undergraduate Honors Thesis

 

Exploring Lipid Biomarker Profiles of Sulfate Reducing Bacteria in Low-Temperature Serpentinizing Systems Utilizing Batch Cultures Public Deposited

https://scholar.colorado.edu/concern/undergraduate_honors_theses/c247dt28m
Abstract
  •      Water-rock reactions sustained in the subsurface of the Samail Ophiolite in Oman create hydrogen and other potential electron donors that can be utilized by microbial metabolisms. Hard rock systems such as Oman have been thought to be analogs for conditions on Mars and other rocky satellites such as Enceladus or Europa. Recently, lipid biomarkers have taken a step into the spotlight as a potential detection method for active and fossil microbial life within extraterrestrial systems such as these. This Honors thesis project seeks to support the findings of PhD student Katie Rempfert’s study of the lipid signatures hosted in the groundwater of the Samail Ophiolite in Oman by giving insight into how the geochemical conditions of the subsurface control the remodeling of the cell membranes of microbial life, such as abundant sulfate reducing bacteria (SRB). To do this I characterized the lipid profiles of Oman groundwater sourced SRBs, as well as a model sulfate reducing bacteria that is closely related to Thermodesulfovibronia: Thermodesulfovibrio aggregans. Then I modulated media conditions to understand how the lipidome changed based on variable temperature and nutrient conditions by observing changes in the compositions of the lipidomes at specific conditions. It was observed through the presence and absence of specific intact polar lipids that SRBs do change the composition of their cell membranes in response to differing conditions. For example, Thermodesulfovibrio aggregans was observed to have PI (phosphatidylinositol) headgroups at high temperatures (55°C) but they were absent at lower temperatures (35°C). It was also found that under all conditions, Thermodesulfovibrioaggregans produce ether bonded lipids such as DEG (dietherglycerol), which has not been reported in the literature previously. 

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  • 2021-04-12
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  • 2021-04-13
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