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Crossen,Kelsey.Masters.thesis.pdf (2.55 MB)

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Investigation of Microbial Community Structure and Functional Groups from Thawing Permafrost Peat Incubations

Crossen, Kelsey B
http://orcid.org/0000-0002-6682-2555
http://rave.ohiolink.edu/etdc/view?acc_num=osu1512033177099274

Abstract Details

2017, Master of Science, Ohio State University, Microbiology.
Permafrost, which stores approximately 50% of global soil carbon, is thawing rapidly due to climate change, and resident microbes are contributing to changing greenhouse gas emissions. Predictions of the fate of carbon in these regions is poorly constrained. However, improved, careful mapping of microbial community members influencing carbon dioxide and methane emissions will help clarify the system response to continued change. In order to more fully understand connections between the microbial communities, major geochemical transformations, and carbon dioxide and methane emissions, peat cores were collected from the active layers of three permafrost habitats spanning a thaw gradient (collapsed palsa, bog, and fen) at Stordalen Mire, Abisko, Sweden. Anaerobic incubations of shallow and deep subsamples from these sites were performed, with time-course characterization of the changes in microbial communities, peat geochemistry, and carbon dioxide and methane production. The former were profiled with 16S rRNA amplicon sequencing, and select metagenomes. The communities within each habitat and depth were statistically distinct, and changed significantly over the course of the incubations. Overall, Acidobacteria was consistently the dominant microbial phylum in incubations from all three habitat types. With increased thaw, the relative abundance of Actinobacteria tended to decrease, while Chloroflexi and Bacteroidetes increased with thaw; these phyla trends are consistent with microbial communities in the field. The relative abundance of methanogens increased with thaw, and with depth in collapsed palsa and bog samples; this is consistent with the later, more inundated thaw stages and deeper depths being more anoxic and providing conditions favorable to methanogens. Additionally, the microbial biodiversity in the incubations decreased over incubation time. Next, we focused on a polyphyletic group of microbes known as homoacetogens. Homoacetogenesis (CO2 + H2 -> CH3COOH) has been documented in other peatlands, and homoacetogens can influence methane production by competing with hydrogenotrophic methanogens for substrate, while providing substrate for acetoclastic methanogens. Collaborators’ work on modelling of microbial reaction networks suggests potential for highest homoacetogenesis rates in incubations of peat material from collapsed palsa and fen, which also contain the highest relative abundances of lineages taxonomically affiliated with known homoacetogens. Counterintuitively, the collapsed palsa has the lowest abundance of acetoclastic methanogens, thus warranting further investigation of the role of homoacetogens. This work will increase knowledge of factors influencing greenhouse gas emissions from this climatically important habitat.
Virginia Rich (Advisor)
Mike Wilkins (Committee Member)
Kelly Wrighton (Committee Member)
101 p.
Microbiology
microbial community; permafrost thaw; incubations

Recommended Citations

Citations

  • Crossen, K. B. (2017). Investigation of Microbial Community Structure and Functional Groups from Thawing Permafrost Peat Incubations [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512033177099274

    APA Style (7th edition)

  • Crossen, Kelsey. Investigation of Microbial Community Structure and Functional Groups from Thawing Permafrost Peat Incubations. 2017. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1512033177099274.

    MLA Style (8th edition)

  • Crossen, Kelsey. "Investigation of Microbial Community Structure and Functional Groups from Thawing Permafrost Peat Incubations." Master's thesis, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1512033177099274

    Chicago Manual of Style (17th edition)

osu1512033177099274
349
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