Molecular biogeochemistry of modern and ancient marine microbes
Waldbauer, Jacob R.
MetadataShow full item record
Biological activity has shaped the surface of the earth in numerous ways, but life’s most pervasive and persistent global impact has been the secular oxidation of the surface environment. Through primary production – the biochemical reduction of carbon dioxide to synthesize biomass – large amounts of oxidants such as molecular oxygen, sulfate and ferric iron have accumulated in the ocean, atmosphere and crust, fundamentally altering the chemical environment of the earth’s surface. This thesis addresses aspects of the role of marine microorganisms in driving this process. In the first section of the thesis, biomarkers (hydrocarbon molecular fossils) are used to investigate the early history of microbial diversity and biogeochemistry. Molecular fossils from the Transvaal Supergroup, South Africa, document the presence in the oceans of a diverse microbiota, including eukaryotes, as well as oxygenic photosynthesis and aerobic biochemistry, by ca. 2.7Ga. Experimental study of the oxygen requirements of steroid biosynthesis suggests that sterane biomarkers in late Archean rocks are consistent with the persistence of microaerobic surface ocean environments long before the initial oxygenation of the atmosphere. In the second part, using Prochlorococcus (a marine cyanobacterium that is the most abundant primary producer on earth today) as a model system, we explored how microbes use the limited nutrient resources available in the marine environment to make the protein catalysts that enable primary production. Quantification of the Prochlorococcus proteome over the diel cell-division cycle reveals that protein abundances are distinct from transcript-level dynamics, and that small temporal shifts in enzyme levels can redirect metabolic fluxes. This thesis illustrates how molecular techniques can contribute to a systems-level understanding of biogeochemical processes, which will aid in reconstructing the past of, and predicting future change in, earth surface environments.
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2010
Suggested CitationThesis: Waldbauer, Jacob R., "Molecular biogeochemistry of modern and ancient marine microbes", 2010-02, DOI:10.1575/1912/3238, https://hdl.handle.net/1912/3238
Showing items related by title, author, creator and subject.
A modeling study of the marine biogeochemistry, plankton dynamics, and carbon cycle on the continental shelf off the West Antarctic Peninsula Schultz, Cristina (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2019-06)Over the past several decades, the West Antarctic Peninsula (WAP) has undergone physical and ecological changes at a rapid pace, with warming surface ocean and a sharp decrease in the duration of the sea ice season. The ...
Pearson, Ann (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1999-10)Compound-specific carbon isotopic (δ13C and Δ14C) data are reported for lipid biomarkers isolated from Santa Monica Basin (SMB) and Santa Barbara Basin (SBB) surface sediments. These organic compounds represent ...
Frame, Caitlin H. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2011-06)Atmospheric nitrous oxide N2O concentrations have been rising steadily for the past century as a result of human activities. In particular, human perturbation of the nitrogen cycle has increased the N2O production rates ...