Decoding DOM Degradation with Metatranscriptomics : How Do Sunlight and Microbial Communities Interact to Degrade Dissolved Organic Matter in Arctic Freshwaters?
Arctic soils are warming, making vast stores of organic carbon available for conversion to CO₂. This could create a positive feedback loop and accelerate global warming, but the processes that convert this carbon into CO₂ are not well understood. We investigated how the combined activities of sunlig...
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ftoregonstate:ir.library.oregonstate.edu:8910jx591 2024-09-09T19:18:05+00:00 Decoding DOM Degradation with Metatranscriptomics : How Do Sunlight and Microbial Communities Interact to Degrade Dissolved Organic Matter in Arctic Freshwaters? Nalven, Sarah G. Crump, Byron C. Sharpton, Thomas J. Myrold, David D. Thurber, Andrew R. College of Earth, Ocean, and Atmospheric Sciences Oregon State University. Graduate School https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/8910jx591 English [eng] eng unknown Oregon State University https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/8910jx591 All rights reserved Soil microbiology -- Arctic regions Microbial metabolism Water -- Organic compound content -- Arctic regions Freshwater microbiology -- Arctic regions Carbon cycle (Biogeochemistry) -- Arctic regions Microorganisms -- Effect of light on -- Arctic regions Gene expression Masters Thesis ftoregonstate 2024-07-22T18:06:07Z Arctic soils are warming, making vast stores of organic carbon available for conversion to CO₂. This could create a positive feedback loop and accelerate global warming, but the processes that convert this carbon into CO₂ are not well understood. We investigated how the combined activities of sunlight and microbes degrade soil dissolved organic matter (DOM), an important component of the carbon processed in arctic freshwaters. DOM leached from the organic layer of moist acidic tundra was exposed to natural sunlight (24 h) or kept in the dark, inoculated and incubated with a soil microbial community, and analyzed for DOM composition (FT-ICR MS) and microbial gene expression (metatranscriptomics). We found that DOM degraded by sunlight was similar in composition to DOM degraded by microbes, and consequently, microbial activity was lower when incubated with sunlight-exposed DOM. We also found sunlight-exposed DOM caused global shifts in both microbial gene expression and the taxonomic groups conducting this expression. Greater expression of transcription and translation genes suggested growth, while lower expression of metabolism, motility, and transport genes suggested reduced investment in scavenging. Photo-exposure of DOM also caused reduced expression of enzymes involved in aromatic degradation, oxygenases, and decarboxylases, suggesting sunlight degraded aromatics, oxidized DOM, and decarboxylated DOM. Shifts in expression of transporters for small, labile compounds and nutrient-containing compounds suggested photo-exposure may have altered bioavailability of these compounds in the DOM pool. These findings demonstrate that even small amounts of sunlight can alter DOM in ways that evoke profound changes in microbial functioning, supporting the idea that sunlight plays a key role in determining the microbial processing of DOM in arctic freshwaters. Master Thesis Arctic Global warming Tundra ScholarsArchive@OSU (Oregon State University) Arctic |
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Open Polar |
collection |
ScholarsArchive@OSU (Oregon State University) |
op_collection_id |
ftoregonstate |
language |
English unknown |
topic |
Soil microbiology -- Arctic regions Microbial metabolism Water -- Organic compound content -- Arctic regions Freshwater microbiology -- Arctic regions Carbon cycle (Biogeochemistry) -- Arctic regions Microorganisms -- Effect of light on -- Arctic regions Gene expression |
spellingShingle |
Soil microbiology -- Arctic regions Microbial metabolism Water -- Organic compound content -- Arctic regions Freshwater microbiology -- Arctic regions Carbon cycle (Biogeochemistry) -- Arctic regions Microorganisms -- Effect of light on -- Arctic regions Gene expression Nalven, Sarah G. Decoding DOM Degradation with Metatranscriptomics : How Do Sunlight and Microbial Communities Interact to Degrade Dissolved Organic Matter in Arctic Freshwaters? |
topic_facet |
Soil microbiology -- Arctic regions Microbial metabolism Water -- Organic compound content -- Arctic regions Freshwater microbiology -- Arctic regions Carbon cycle (Biogeochemistry) -- Arctic regions Microorganisms -- Effect of light on -- Arctic regions Gene expression |
description |
Arctic soils are warming, making vast stores of organic carbon available for conversion to CO₂. This could create a positive feedback loop and accelerate global warming, but the processes that convert this carbon into CO₂ are not well understood. We investigated how the combined activities of sunlight and microbes degrade soil dissolved organic matter (DOM), an important component of the carbon processed in arctic freshwaters. DOM leached from the organic layer of moist acidic tundra was exposed to natural sunlight (24 h) or kept in the dark, inoculated and incubated with a soil microbial community, and analyzed for DOM composition (FT-ICR MS) and microbial gene expression (metatranscriptomics). We found that DOM degraded by sunlight was similar in composition to DOM degraded by microbes, and consequently, microbial activity was lower when incubated with sunlight-exposed DOM. We also found sunlight-exposed DOM caused global shifts in both microbial gene expression and the taxonomic groups conducting this expression. Greater expression of transcription and translation genes suggested growth, while lower expression of metabolism, motility, and transport genes suggested reduced investment in scavenging. Photo-exposure of DOM also caused reduced expression of enzymes involved in aromatic degradation, oxygenases, and decarboxylases, suggesting sunlight degraded aromatics, oxidized DOM, and decarboxylated DOM. Shifts in expression of transporters for small, labile compounds and nutrient-containing compounds suggested photo-exposure may have altered bioavailability of these compounds in the DOM pool. These findings demonstrate that even small amounts of sunlight can alter DOM in ways that evoke profound changes in microbial functioning, supporting the idea that sunlight plays a key role in determining the microbial processing of DOM in arctic freshwaters. |
author2 |
Crump, Byron C. Sharpton, Thomas J. Myrold, David D. Thurber, Andrew R. College of Earth, Ocean, and Atmospheric Sciences Oregon State University. Graduate School |
format |
Master Thesis |
author |
Nalven, Sarah G. |
author_facet |
Nalven, Sarah G. |
author_sort |
Nalven, Sarah G. |
title |
Decoding DOM Degradation with Metatranscriptomics : How Do Sunlight and Microbial Communities Interact to Degrade Dissolved Organic Matter in Arctic Freshwaters? |
title_short |
Decoding DOM Degradation with Metatranscriptomics : How Do Sunlight and Microbial Communities Interact to Degrade Dissolved Organic Matter in Arctic Freshwaters? |
title_full |
Decoding DOM Degradation with Metatranscriptomics : How Do Sunlight and Microbial Communities Interact to Degrade Dissolved Organic Matter in Arctic Freshwaters? |
title_fullStr |
Decoding DOM Degradation with Metatranscriptomics : How Do Sunlight and Microbial Communities Interact to Degrade Dissolved Organic Matter in Arctic Freshwaters? |
title_full_unstemmed |
Decoding DOM Degradation with Metatranscriptomics : How Do Sunlight and Microbial Communities Interact to Degrade Dissolved Organic Matter in Arctic Freshwaters? |
title_sort |
decoding dom degradation with metatranscriptomics : how do sunlight and microbial communities interact to degrade dissolved organic matter in arctic freshwaters? |
publisher |
Oregon State University |
url |
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/8910jx591 |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic Global warming Tundra |
genre_facet |
Arctic Global warming Tundra |
op_relation |
https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/8910jx591 |
op_rights |
All rights reserved |
_version_ |
1809758186690838528 |