2022 Fiscal Year Annual Research Report
Study of marine carbon cycle based on stable carbon isotopic compositions of amino acids in marine sediments
| Project/Area Number |
21J20841
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| Allocation Type | Single-year Grants |
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| Research Institution | The University of Tokyo |
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Principal Investigator |
孫 語辰 東京大学, 理学系研究科, 特別研究員(DC1)
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| Project Period (FY) |
2021-04-28 – 2024-03-31
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| Keywords | amino acid / marine sediment / microbial reworking / organic matter |
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| Outline of Annual Research Achievements |
This research aims to elucidate the dynamics and mechanism of organic matter preservation and degradation in marine sediments, using carbon isotopic compositions of amino acids as the main tool.
In this year, I further modified the analytical method for isotope analyses of amino acids in marine sediment samples. I applied a new HPLC column, Hypercarb column, for the separation of amino acids. Finally, I achieved the successful analyses of individual hydrophilic amino acids in marine sediments, which cannot be achieved by the previous method. I confirmed the analyses by testing amino acid standards. This method also shows the potential for other isotope analyses, such as nitrogen isotope and radiocarbon, which would benefit future researches on environmental amino acids.
Furthermore, I developed a new method for the isolation of individual D-amino acids in environmental samples using a chiral HPLC column, and confirmed the reliability of stable carbon and nitrogen isotope analyses. This method can be applied to study the D-amino acids in marine sediments, which can be potentially used as a microbial biomarker to study the sources and transformations of organic matter under the sea floor in the future.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
In this year, by modifying the analytical method, I successfully achieved the analyses of hydrophilic amino acids in samples with complex matrices. It enables future analyses of amino acids in marine sediments. Furthermore, I successfully developed a new method for the analyses of D-amino acids, which can be potentially used as a microbial biomarker of sedimentary organic matter in the future. These two achievements have been summarized and two manuscripts are in preparation, which will be submitted to international journals. So, although the number of sediment samples analyzed is still limited, the program is now generally proceeding smoothly.
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| Strategy for Future Research Activity |
In the next year, I will apply the newly developed method to the analyses of more marine sediment samples. In the first year, I analyzed stable carbon isotopic compositions of amino acids in four sediment samples from two sediment cores taken from NW Pacific and Japan Sea, and found that stable carbon isotope compositions of amino acids in these samples have very similar patterns. In the next year, I will analyze more sediment samples from these two cores to achieve a higher time resolution. Moreover, I will study the hydrophilic amino acids and D-amino acids using the new method, in order to construct a more representative model covering a wider range of amino acids.
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