| Project/Area Number |
23K19390
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| Research Category |
Grant-in-Aid for Research Activity Start-up
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| Allocation Type | Multi-year Fund |
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| Review Section |
0703:Biology at organismal to population levels and anthropology, and related fields
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| Research Institution | Japan Agency for Marine-Earth Science and Technology |
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Principal Investigator |
TSUJI JACKSON・MAKOTO 国立研究開発法人海洋研究開発機構, 超先鋭研究開発部門(超先鋭研究開発プログラム), Young Research Fellow (60976207)
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| Project Period (FY) |
2023-08-31 – 2025-03-31
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| Project Status |
Granted (Fiscal Year 2023)
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| Budget Amount *help |
¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2024: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2023: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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| Keywords | Photosynthesis / Phototrophy / Iron cycling / Evolution / Archaean ocean / Biogeochemistry / Chloroflexi / Chloroflexota / Iron / Microbiology |
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| Outline of Research at the Start |
This project will combine geochemical, biochemical, and DNA-based tools to probe how a novel bacterium (strain L227-S17) uses light energy to "eat" iron. Results from this project will give new insights into how photosynthesis may have sustained life in the iron-rich oceans of the ancient Earth.
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| Outline of Annual Research Achievements |
This project seeks to probe the physiological basis of light-driven iron oxidation by a highly novel “living fossil” bacterium, “Candidatus Chlorohelix allophototropha” strain L227-S17. In FY2023, we made important progress in understanding the metabolism of this strain. When attempting to demonstrate light-driven iron oxidation in the laboratory, we initially encountered several challenges related to reproducible cultivation of strain L227-S17. We needed to use a gel-like matrix material to robustly grow strain L227-S17 cells, but iron compounds adhered to this matrix, preventing accurate measurements. To overcome these challenges, we optimized a growth protocol for strain L227-S17 that, based on a pilot experiment, allows for robust cell growth and reproducible recovery of iron. This growth protocol will be used in FY2024 to monitor iron and carbon transformations in the culture. In a pioneering experiment, we also used biomass recovered from this optimized growth protocol to attempt to purify the photosynthetic complexes of strain L227-S17 using native polyacrylamide gel electrophoresis (native-PAGE). Mass spectrometry will be used in FY2024 to analyze the purified complexes to give a new view of the proteins that drive photosynthesis by this highly novel bacterium. Alongside biochemical analyses, we used cutting-edge bioinformatics approaches to predict the photosynthetic electron transport chain used by strain L227-S17, and these data were included in a publication that describes our discovery and cultivation of the strain (Tsuji et al., Nature, 2024).
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
Unexpected challenges with reproducible cultivation of strain L227-S17, as mentioned in the Summary of Research Achievements, meant that we needed to invest more time than anticipated to optimize a growth protocol for the strain. We were unable to perform stable isotope tracer analyses, X-ray spectroscopy analyses, and transcriptomic analyses of strain L227-S17 in FY2023 because of these delays. Now that an optimized growth protocol is in place, we plan to begin cultivation experiments for transcriptomic and X-ray spectroscopic analyses in early FY2024, and we plan to perform the carbon stable isotope experiment in mid FY2024.
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| Strategy for Future Research Activity |
Delays in cultivation work meant that we needed to postpone some experiments compared to the original research plan (see the Current Status section). However, we expect to still meet most primary research goals of this project by the end of FY2024. Our key cultivation-based test of iron oxidation by strain L227-S17 will begin in early FY2024, and we expect transcriptome and X-ray spectroscopy data to be available from this test in mid FY2024. Transcriptome data will then be integrated into phylogenomic analyses of the Chloroflexota phylum to understand the evolutionary history of iron oxidation gene candidates within the phylum. If time permits, our analysis of iron oxidation gene candidates will then be expanded across all bacteria as originally planned. Genetic data will be integrated with carbon stable isotope tracer data (available in mid to late FY2024) and X-ray spectroscopy data to give a holistic view of iron oxidation by strain L227-S17. Due to cultivation challenges and high biomass requirements for isolation of chlorosomes using standard methods, we began our biochemical work by attempting to purify whole photosynthetic complexes from strain L227-S17 using an alternative approach, native-PAGE. This native-PAGE approach seems promising based on early results. In FY2024, we might pivot more of our biochemical work to focus on native-PAGE, depending on available biomass. Our discovery of strain L227-S17 is also generating substantial interest in our work among the scientific community, leading us to travel to additional academic conferences to present our findings.
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