Characterizing cobalamin cycling by Antarctic marine microbes across multiple scales
Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), May, 2020 Cataloged from the official PDF of thesis. Includes bibliogra...
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ftmit:oai:dspace.mit.edu:1721.1/127908 2023-06-11T04:06:06+02:00 Characterizing cobalamin cycling by Antarctic marine microbes across multiple scales Rao, Deepa,Ph.D.Massachusetts Institute of Technology. Michael J. Follows. Joint Program in Oceanography/Applied Ocean Science and Engineering. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences. Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Woods Hole Oceanographic Institution 2020 183 pages application/pdf https://hdl.handle.net/1721.1/127908 eng eng Massachusetts Institute of Technology https://hdl.handle.net/1721.1/127908 1197629828 MIT theses may be protected by copyright. Please reuse MIT thesis content according to the MIT Libraries Permissions Policy, which is available through the URL provided. http://dspace.mit.edu/handle/1721.1/7582 Joint Program in Oceanography/Applied Ocean Science and Engineering Earth Atmospheric and Planetary Sciences Woods Hole Oceanographic Institution Thesis 2020 ftmit 2023-05-29T08:37:01Z Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), May, 2020 Cataloged from the official PDF of thesis. Includes bibliographical references (pages 161-183). Highly productive marine microbial communities in the coastal Southern Ocean sustain the broader Antarctic ecosystem and play a key role in Earth's climate via the biological pump. Regional phytoplankton growth is primarily limited by iron and co-limited by cobalamin (vitamin B₁₂), a trace cobalt-containing organometallic compound only synthesized by some bacteria and archaea. These micronutrients impact primary production and the microbial ecology of the two keystone phytoplankton types: diatoms and Phaeocystis antarctica. This thesis investigates microbe-driven cobalamin cycling in Antarctic seas across multiple spatiotemporal scales. I conducted laboratory culture experiments with complementary proteomics and transcriptomics to investigate the B₁₂-ecophysiology of P. antarctica strain CCMP 1871 morphotypes under iron-B₁₂ co-limitation. We observed colony formation under higher iron treatments, and a facultative use of B₁₂-dependent (MetH) and B₁₂-independent (MetE) methionine synthase isoforms in response to vitamin availability, demonstrating that this strain is not B₁₂-auxotrophic. Through comparative 'omics, we identified a putative MetE protein in P. antarctica abundant under low B₁₂, which is also found in other marine microbes. Across Antarctic seas, community-scale cobalt and B₁₂ uptake rates were measured by ⁵⁷Co radiotracer incubation experiments and integrated with hydrographic and phytoplankton pigment data. I observed significant correlations between uptake fluxes and environmental variables, providing evidence for predominantly diatom-driven uptake of these micronutrients in warmer, fresher surface waters with notable regional differences. To date, this work ... Thesis Antarc* Antarctic Antarctica Southern Ocean DSpace@MIT (Massachusetts Institute of Technology) Antarctic Southern Ocean |
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DSpace@MIT (Massachusetts Institute of Technology) |
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English |
topic |
Joint Program in Oceanography/Applied Ocean Science and Engineering Earth Atmospheric and Planetary Sciences Woods Hole Oceanographic Institution |
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Joint Program in Oceanography/Applied Ocean Science and Engineering Earth Atmospheric and Planetary Sciences Woods Hole Oceanographic Institution Rao, Deepa,Ph.D.Massachusetts Institute of Technology. Characterizing cobalamin cycling by Antarctic marine microbes across multiple scales |
topic_facet |
Joint Program in Oceanography/Applied Ocean Science and Engineering Earth Atmospheric and Planetary Sciences Woods Hole Oceanographic Institution |
description |
Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), May, 2020 Cataloged from the official PDF of thesis. Includes bibliographical references (pages 161-183). Highly productive marine microbial communities in the coastal Southern Ocean sustain the broader Antarctic ecosystem and play a key role in Earth's climate via the biological pump. Regional phytoplankton growth is primarily limited by iron and co-limited by cobalamin (vitamin B₁₂), a trace cobalt-containing organometallic compound only synthesized by some bacteria and archaea. These micronutrients impact primary production and the microbial ecology of the two keystone phytoplankton types: diatoms and Phaeocystis antarctica. This thesis investigates microbe-driven cobalamin cycling in Antarctic seas across multiple spatiotemporal scales. I conducted laboratory culture experiments with complementary proteomics and transcriptomics to investigate the B₁₂-ecophysiology of P. antarctica strain CCMP 1871 morphotypes under iron-B₁₂ co-limitation. We observed colony formation under higher iron treatments, and a facultative use of B₁₂-dependent (MetH) and B₁₂-independent (MetE) methionine synthase isoforms in response to vitamin availability, demonstrating that this strain is not B₁₂-auxotrophic. Through comparative 'omics, we identified a putative MetE protein in P. antarctica abundant under low B₁₂, which is also found in other marine microbes. Across Antarctic seas, community-scale cobalt and B₁₂ uptake rates were measured by ⁵⁷Co radiotracer incubation experiments and integrated with hydrographic and phytoplankton pigment data. I observed significant correlations between uptake fluxes and environmental variables, providing evidence for predominantly diatom-driven uptake of these micronutrients in warmer, fresher surface waters with notable regional differences. To date, this work ... |
author2 |
Michael J. Follows. Joint Program in Oceanography/Applied Ocean Science and Engineering. Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences. Woods Hole Oceanographic Institution. Joint Program in Oceanography/Applied Ocean Science and Engineering Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences Woods Hole Oceanographic Institution |
format |
Thesis |
author |
Rao, Deepa,Ph.D.Massachusetts Institute of Technology. |
author_facet |
Rao, Deepa,Ph.D.Massachusetts Institute of Technology. |
author_sort |
Rao, Deepa,Ph.D.Massachusetts Institute of Technology. |
title |
Characterizing cobalamin cycling by Antarctic marine microbes across multiple scales |
title_short |
Characterizing cobalamin cycling by Antarctic marine microbes across multiple scales |
title_full |
Characterizing cobalamin cycling by Antarctic marine microbes across multiple scales |
title_fullStr |
Characterizing cobalamin cycling by Antarctic marine microbes across multiple scales |
title_full_unstemmed |
Characterizing cobalamin cycling by Antarctic marine microbes across multiple scales |
title_sort |
characterizing cobalamin cycling by antarctic marine microbes across multiple scales |
publisher |
Massachusetts Institute of Technology |
publishDate |
2020 |
url |
https://hdl.handle.net/1721.1/127908 |
geographic |
Antarctic Southern Ocean |
geographic_facet |
Antarctic Southern Ocean |
genre |
Antarc* Antarctic Antarctica Southern Ocean |
genre_facet |
Antarc* Antarctic Antarctica Southern Ocean |
op_relation |
https://hdl.handle.net/1721.1/127908 1197629828 |
op_rights |
MIT theses may be protected by copyright. Please reuse MIT thesis content according to the MIT Libraries Permissions Policy, which is available through the URL provided. http://dspace.mit.edu/handle/1721.1/7582 |
_version_ |
1768377861053349888 |