MEES Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/19655

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    THE PROBIOTICS OF BIOFUEL: A METAGENOMIC STUDY OF MICROALGAE GROWN FOR FUEL PRODUCTION
    (2018) Major, Samuel; Hill, Russell T; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Ponds in Frederick, MD were fertilized with chicken manure to increase the nutrient load in the water and stimulate microalgal growth. Nutrient analyses indicate that fertilization results in significant increases in the DOC, TDN, and TDP. The bacterial and eukaryotic microalgal communities were analyzed using 16S and 18S rRNA gene sequencing, respectively. Communities were analyzed pre-fertilization and for 15 days following fertilization. Molecular data reveals a decrease in diversity as microalgal blooms form. The microalgal density increased following fertilization, with enrichment for the Chlamydomonadales order. Prior to fertilization the bacterial communities were dominated by five phyla: Actinobacteria, Bacteroidetes, Cyanobacteria, Proteobacteria, and Verrucomicrobia. Dominant bacterial genera post-fertilization included Flavobacterium, Limnohabitans, and Polynucleobacter. Bacteria isolated from the ponds were screened for effects on Scenedesmus sp. HTB1 to identify bacteria that either enhance or inhibit microalgal growth. The growth-promoting bacteria were closely related to bacteria found to be enriched during microalgal bloom formation.
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    A Proteomics Approach to the Examination of Proteins in Marine Systems
    (2014) Faux, Jessica Felicia; Harvey, Henry R; Marine-Estuarine-Environmental Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The response of global carbon and nitrogen cycles to future climate change is uncertain. In order to understand the impacts that future changes to climate will have on these cycles, a more detailed understanding of them is essential. This dissertation utilizes a combined approach of molecular biomarkers and proteomic investigations to elucidate historic source material contributions and microbial protein production to contribute to a more thorough understanding of the marine carbon and nitrogen cycles. The examination of molecular organic biomarkers throughout an Arctic sediment core showed the dominant input in the area was from marine sources with lower but steady contributions from terrestrial sources during the Holocene. Attempts to recover proteins from deeper sediments to correlate with lipid biomarkers were unsuccessful but led to the optimization of an extraction protocol for an added protein standard, bovine serum albumin, from sediments. An investigation into the expressed proteome of the heterotrophic marine bacterium, Ruegeria pomeroyi, under environmentally realistic carbon supply conditions during exponential and stationary growth phases identified over 2000 proteins. The most abundant proteins identified were responsible for porins, transport, binding, translation, and protein refolding and could represent potential biomarkers of bacterial processes and/or activity. A parallel study of R. pomeroyi, in which 13C-labeled leucine was added to the culture during exponential growth phase, showed labeled incorporation ranging from 16 to 21% of the total proteins produced depending on growth phase. The widespread distribution of the label among the growth phases indicates active recycling by the bacteria. This study demonstrates a method through which bacterial protein synthesis can be tracked. A study of the marine diatom Thalassiosira pseudonana acclimated to iron replete or iron-limited conditions showed iron-limited organisms increased proteins involved in pathways associated with intracellular protein recycling, the pentose phosphate pathway, lower photosynthetic energy production, enhancement of photorespiration, and increased polysaccharide production. This application of proteomics to the examination of proteins in marine sediments, a marine diatom, and a heterotrophic marine bacterium shows the potential for these techniques to help elucidate the fate of proteins in marine environments and could be used in conjunction with well-established molecular organic marker studies.