Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine
<p><i>Phragmites australis</i> litters were incubated in three waterlogged anoxic wetland soils of different nutrient status for 75 <span class="inline-formula">d</span>, and litter nitrogen (N) dynamics were analyzed by elemental analyses and Fouri...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2020-01-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/17/499/2020/bg-17-499-2020.pdf |
| _version_ | 1831636611784245248 |
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| author | H. Reuter J. Gensel M. Elvert D. Zak |
| author_facet | H. Reuter J. Gensel M. Elvert D. Zak |
| author_sort | H. Reuter |
| collection | DOAJ |
| description | <p><i>Phragmites australis</i> litters were incubated in three waterlogged anoxic wetland soils of different nutrient status for 75 <span class="inline-formula">d</span>, and litter nitrogen (N) dynamics were analyzed by elemental analyses and Fourier transform infrared spectroscopy (FTIR). At the end of the incubation time, the N content in the remaining litter tissue had increased in most samples. Yet, the increase in N content was less pronounced when litters had been decomposed in a more-N-poor environment. FTIR was used to quantify the relative content of proteins in litter tissue and revealed a highly linear relationship between bulk N content and protein content. Changes in bulk N content thus paralleled and probably were governed by changes in litter protein content. Such changes are the result of two competing processes within decomposing litter: enzymatic protein depolymerization as a part of the litter breakdown process and microbial protein synthesis as a part of microbial biomass growth within the litter. Assuming microbial homeostasis, DNA signals in FTIR spectra were used to calculate the amount of microbial N in decomposed litter which ranged from 14 % to 42 % of the total litter N for all leaf samples. Microbial carbon (C) content and resultant calculated carbon use efficiencies (CUEs) indicate that microbial N in litter accumulated according to predictions of the stoichiometric decomposition theory. Subtracting microbial C and N contributions from litter, however, revealed site-dependent variations in the percentual amount of the remaining still-unprocessed plant N in litter compared to remaining plant C, an indicator for preferential protein depolymerization. For all leaf litters, the coefficient of preferential protein depolymerization (<span class="inline-formula"><i>α</i></span>), which relates N-compound depolymerization to C-compound depolymerization, ranged from 0.74–0.88 in a nutrient-rich detritus mud to 1.38–1.82 in <i>Sphagnum</i> peat, the most nutrient-poor substrate in this experiment. Preferential protein depolymerization from litter decomposing in <i>Sphagnum</i> peat leads to a gradual N depletion in the early phase of litter decomposition, which we propose as a preservation mechanism for vascular litter in <i>Sphagnum</i> peatlands.</p> |
| first_indexed | 2024-12-19T06:36:25Z |
| format | Article |
| id | doaj.art-d1289c320026400e8ee755248fd54ac2 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-19T06:36:25Z |
| publishDate | 2020-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-d1289c320026400e8ee755248fd54ac22022-12-21T20:32:14ZengCopernicus PublicationsBiogeosciences1726-41701726-41892020-01-011749951410.5194/bg-17-499-2020Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routineH. Reuter0J. Gensel1M. Elvert2D. Zak3Department of Chemical Analytics and Biogeochemistry, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, 12587 Berlin, GermanyMARUM – Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, 28359 Bremen, GermanyMARUM – Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, 28359 Bremen, GermanyDepartment of Bioscience, University of Aarhus, 8600 Silkeborg, Denmark<p><i>Phragmites australis</i> litters were incubated in three waterlogged anoxic wetland soils of different nutrient status for 75 <span class="inline-formula">d</span>, and litter nitrogen (N) dynamics were analyzed by elemental analyses and Fourier transform infrared spectroscopy (FTIR). At the end of the incubation time, the N content in the remaining litter tissue had increased in most samples. Yet, the increase in N content was less pronounced when litters had been decomposed in a more-N-poor environment. FTIR was used to quantify the relative content of proteins in litter tissue and revealed a highly linear relationship between bulk N content and protein content. Changes in bulk N content thus paralleled and probably were governed by changes in litter protein content. Such changes are the result of two competing processes within decomposing litter: enzymatic protein depolymerization as a part of the litter breakdown process and microbial protein synthesis as a part of microbial biomass growth within the litter. Assuming microbial homeostasis, DNA signals in FTIR spectra were used to calculate the amount of microbial N in decomposed litter which ranged from 14 % to 42 % of the total litter N for all leaf samples. Microbial carbon (C) content and resultant calculated carbon use efficiencies (CUEs) indicate that microbial N in litter accumulated according to predictions of the stoichiometric decomposition theory. Subtracting microbial C and N contributions from litter, however, revealed site-dependent variations in the percentual amount of the remaining still-unprocessed plant N in litter compared to remaining plant C, an indicator for preferential protein depolymerization. For all leaf litters, the coefficient of preferential protein depolymerization (<span class="inline-formula"><i>α</i></span>), which relates N-compound depolymerization to C-compound depolymerization, ranged from 0.74–0.88 in a nutrient-rich detritus mud to 1.38–1.82 in <i>Sphagnum</i> peat, the most nutrient-poor substrate in this experiment. Preferential protein depolymerization from litter decomposing in <i>Sphagnum</i> peat leads to a gradual N depletion in the early phase of litter decomposition, which we propose as a preservation mechanism for vascular litter in <i>Sphagnum</i> peatlands.</p>https://www.biogeosciences.net/17/499/2020/bg-17-499-2020.pdf |
| spellingShingle | H. Reuter J. Gensel M. Elvert D. Zak Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine Biogeosciences |
| title | Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine |
| title_full | Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine |
| title_fullStr | Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine |
| title_full_unstemmed | Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine |
| title_short | Evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel FTIR routine |
| title_sort | evidence for preferential protein depolymerization in wetland soils in response to external nitrogen availability provided by a novel ftir routine |
| url | https://www.biogeosciences.net/17/499/2020/bg-17-499-2020.pdf |
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