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Microbial Carbon and Sulfur Cycling in Prairie Pothole Wetlands

Dalcin Martins, Paula
http://orcid.org/0000-0003-1242-0267
http://rave.ohiolink.edu/etdc/view?acc_num=osu1531497726450956

Abstract Details

2018, Doctor of Philosophy, Ohio State University, Microbiology.
The Prairie Pothole Region (PPR) of North America is the tenth largest wetland ecosystem in the world. In Chapter 1, an overview of this region is provided, focusing on key biogeochemical aspects of this region. Additionally, themes explored throughout this document, such as sulfate reduction, methanogenesis, the role of viruses in biogeochemical cycles, and microbial alcohol metabolism, are briefly reviewed. Chapter 2 presents the first study of coupled geochemistry and microbiology in wetlands within the PPR, extremely high methane emissions, and the highest sulfate reduction rates measured to date. Our results also highlighted the dynamic spatiotemporal changes that occur in microbial communities and organic carbon pools in these sediments. Particularly, millimolar concentrations of ethanol and isopropanol measured in spring samples became depleted over summer. These surprising observations and measurements stimulated the detailed investigation of microbial community members, potential factors controlling biogeochemical processes, and key intermediates in organic matter degradation that are presented in the following chapters. Chapter 3 investigates which microorganisms are likely responsible for sulfate reduction and methanogenesis, investigating viral and metabolic controls on activity rates. From hundreds of recovered marker gene sequences and metagenome-assembled genomes, we identified phylogenetic and metabolic diversity in candidate sulfate reducers and methanogens, which had the inferred capability of utilizing the abundant alcohols measured in our first study, as well as methylated compounds and small organic molecules. Viral sequences were novel and abundant, and were predicted to target abundant candidate sulfate reducers and methanogens. We suggested that the inferred genomic diversity and metabolic versatility, viral infections, and niche differentiation likely play an important role in modulating carbon and sulfur cycling in this ecosystem. Chapter 4 explores how alcohols measured in high concentrations in PPR wetland sediments could be generated. We constructed an alcohol dehydrogenase (ADH) phylogenetic tree that allowed us to infer the substrate preference of ADHs present in genomes of candidate alcohol-cycling microorganisms. We identified 62 genomes from 16 phylum-level groups which had potential for alcohol cycling, including 14 genomes encoding putative isopropanol dehydrogenases. Moreover, we performed a detailed investigation of pathways accounting for alcohol fermentation. The potential for acetone/isopropanol-butanol-ethanol fermentation was not clear, and the role of putative isopropanol dehydrogenases in these genomes deserves further investigation. These results are the first insights into alcohol production in Prairie Pothole wetlands and represent an exciting new venue of research in wetland carbon cycling, with important biotechnological applications. Chapter 5 summarizes the main findings, conclusions and implications of this research, discussing questions that need to be addressed in future studies. Particularly, we concluded that metabolic versatility at both the organism and the microbial community level may be one of the key mechanisms underlying the high production and emissions of greenhouse gases in Prairie Pothole wetlands. Our results have implications to a variety of analogous terrestrial and marine environments and advance the field of wetland microbiology and biogeochemistry, providing insights that may be integrated into future climate change models.
Michael Wilkins, Dr. (Advisor)
Birgit Alber, Dr. (Committee Member)
Matthew Sullivan, Dr. (Committee Member)
Yu-Ping Chin, Dr. (Committee Member)
181 p.
Microbiology
methanogenesis; sulfate reduction; viruses; alcohols; fermentation; Prairie Pothole Region

Recommended Citations

Citations

  • Dalcin Martins, P. (2018). Microbial Carbon and Sulfur Cycling in Prairie Pothole Wetlands [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531497726450956

    APA Style (7th edition)

  • Dalcin Martins, Paula. Microbial Carbon and Sulfur Cycling in Prairie Pothole Wetlands. 2018. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1531497726450956.

    MLA Style (8th edition)

  • Dalcin Martins, Paula. "Microbial Carbon and Sulfur Cycling in Prairie Pothole Wetlands." Doctoral dissertation, Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1531497726450956

    Chicago Manual of Style (17th edition)

osu1531497726450956
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This open access ETD is published by The Ohio State University and OhioLINK.