Fractionation of hydrogen isotopes by sulfate- and nitrate-reducing bacteria
Hydrogen atoms from water and food are incorporated into biomass during cellular metabolism and biosynthesis, fractionating the isotopes of hydrogen –protium and deuterium –that are recorded in biomolecules. While these fractionations are often relatively constant in plants, large variations in the...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2016-08-01
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| Series: | Frontiers in Microbiology |
| Subjects: | |
| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fmicb.2016.01166/full |
| _version_ | 1818838578122194944 |
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| author | Magdalena Rose Osburn Katherine S Dawson Marilyn L Fogel Alex Sessions |
| author_facet | Magdalena Rose Osburn Katherine S Dawson Marilyn L Fogel Alex Sessions |
| author_sort | Magdalena Rose Osburn |
| collection | DOAJ |
| description | Hydrogen atoms from water and food are incorporated into biomass during cellular metabolism and biosynthesis, fractionating the isotopes of hydrogen –protium and deuterium –that are recorded in biomolecules. While these fractionations are often relatively constant in plants, large variations in the magnitude of fractionation are observed for many heterotrophic microbes utilizing different central metabolic pathways. The correlation between metabolism and lipid δ2H provides a potential basis for reconstructing environmental and ecological parameters, but the calibration dataset has thus far been limited mainly to aerobes. Here we report on the hydrogen isotopic fractionations of lipids produced by nitrate-respiring and sulfate-reducing bacteria. We observe only small differences in fractionation between oxygen- and nitrate-respiring growth conditions, with a typical pattern of variation between substrates that is broadly consistent with previously described trends. In contrast, fractionation by sulfate-reducing bacteria does not vary significantly between different substrates, even when autotrophic and heterotrophic growth conditions are compared. This result is in marked contrast to previously published observations and has significant implications for the interpretation of environmental hydrogen isotope data. We evaluate these trends in light of metabolic gene content of each strain, growth rate, and potential flux and reservoir-size effects of cellular hydrogen, but find no single variable that can account for the differences between nitrate- and sulfate-respiring bacteria. The emerging picture of bacterial hydrogen isotope fractionation is therefore more complex than the simple correspondence between δ2H and metabolic pathway previously understood from aerobes. Despite the complexity, the large signals and rich variability of observed lipid δ2H suggest much potential as an environmental recorder of metabolism. |
| first_indexed | 2024-12-19T03:40:37Z |
| format | Article |
| id | doaj.art-6c36bd488772419ebdb8f73ec3b238c4 |
| institution | Directory Open Access Journal |
| issn | 1664-302X |
| language | English |
| last_indexed | 2024-12-19T03:40:37Z |
| publishDate | 2016-08-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Microbiology |
| spelling | doaj.art-6c36bd488772419ebdb8f73ec3b238c42022-12-21T20:37:15ZengFrontiers Media S.A.Frontiers in Microbiology1664-302X2016-08-01710.3389/fmicb.2016.01166196727Fractionation of hydrogen isotopes by sulfate- and nitrate-reducing bacteriaMagdalena Rose Osburn0Katherine S Dawson1Marilyn L Fogel2Alex Sessions3Northwestern UniversityCalifornia Institute of TechnologyUniversity of California at MercedCalifornia Institute of TechnologyHydrogen atoms from water and food are incorporated into biomass during cellular metabolism and biosynthesis, fractionating the isotopes of hydrogen –protium and deuterium –that are recorded in biomolecules. While these fractionations are often relatively constant in plants, large variations in the magnitude of fractionation are observed for many heterotrophic microbes utilizing different central metabolic pathways. The correlation between metabolism and lipid δ2H provides a potential basis for reconstructing environmental and ecological parameters, but the calibration dataset has thus far been limited mainly to aerobes. Here we report on the hydrogen isotopic fractionations of lipids produced by nitrate-respiring and sulfate-reducing bacteria. We observe only small differences in fractionation between oxygen- and nitrate-respiring growth conditions, with a typical pattern of variation between substrates that is broadly consistent with previously described trends. In contrast, fractionation by sulfate-reducing bacteria does not vary significantly between different substrates, even when autotrophic and heterotrophic growth conditions are compared. This result is in marked contrast to previously published observations and has significant implications for the interpretation of environmental hydrogen isotope data. We evaluate these trends in light of metabolic gene content of each strain, growth rate, and potential flux and reservoir-size effects of cellular hydrogen, but find no single variable that can account for the differences between nitrate- and sulfate-respiring bacteria. The emerging picture of bacterial hydrogen isotope fractionation is therefore more complex than the simple correspondence between δ2H and metabolic pathway previously understood from aerobes. Despite the complexity, the large signals and rich variability of observed lipid δ2H suggest much potential as an environmental recorder of metabolism.http://journal.frontiersin.org/Journal/10.3389/fmicb.2016.01166/fullFatty AcidsNAD(P)Hsulfate-reducing bacteriahydrogen isotopesAnaerobic microbial metabolismtranshydrogenase. |
| spellingShingle | Magdalena Rose Osburn Katherine S Dawson Marilyn L Fogel Alex Sessions Fractionation of hydrogen isotopes by sulfate- and nitrate-reducing bacteria Frontiers in Microbiology Fatty Acids NAD(P)H sulfate-reducing bacteria hydrogen isotopes Anaerobic microbial metabolism transhydrogenase. |
| title | Fractionation of hydrogen isotopes by sulfate- and nitrate-reducing bacteria |
| title_full | Fractionation of hydrogen isotopes by sulfate- and nitrate-reducing bacteria |
| title_fullStr | Fractionation of hydrogen isotopes by sulfate- and nitrate-reducing bacteria |
| title_full_unstemmed | Fractionation of hydrogen isotopes by sulfate- and nitrate-reducing bacteria |
| title_short | Fractionation of hydrogen isotopes by sulfate- and nitrate-reducing bacteria |
| title_sort | fractionation of hydrogen isotopes by sulfate and nitrate reducing bacteria |
| topic | Fatty Acids NAD(P)H sulfate-reducing bacteria hydrogen isotopes Anaerobic microbial metabolism transhydrogenase. |
| url | http://journal.frontiersin.org/Journal/10.3389/fmicb.2016.01166/full |
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