| Project/Area Number |
16370014
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Ecology/Environment
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| Research Institution | Hokkaido University |
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Principal Investigator |
FUKUI Manabu Hokkaido University, Institute of Low Temperature Science, Professor (60305414)
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| Co-Investigator(Kenkyū-buntansha) |
KOJIMA Hisaya Hokkaido University, Institute of Low Temperature Science, Assi. Prof. (70400009)
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| Project Period (FY) |
2004 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥16,190,000 (Direct Cost: ¥15,500,000、Indirect Cost: ¥690,000)
Fiscal Year 2007: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000)
Fiscal Year 2006: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2005: ¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2004: ¥7,200,000 (Direct Cost: ¥7,200,000)
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| Keywords | Sulfur / Phylogenetic evolution / Molecular evolution / Thermophile / Microorganism / Sulfate reduction / Sulfur oxidation / Functional gene |
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| Research Abstract |
Microbial sulfate reduction is recorded in 〜3.47-Gyr-old barites from North Pole, Australia (Shen et al., 2001: Nature 401, 77-81), indicating that emergence of sulfate-reducing bacteria was earlier than we thought. However, it is unclear how various types of sulfur cycle and sulfur-metabolizing microorganism co-evolve in the present aquatic ecosystems. Aims of this study was first to compare phylogenetic relationship among sulfur-metabolizing microorganisms inhabiting high-temperature terrestrial hot springs, a moderate-temperature meromictic saline lake and a moderate-temperature freshwater oligotrophic lake, second to infer the origin of microbial sulfur cycle, and finally to understand the successive development of the sulfur cycle systems throughout Earth history. By phylogenetic and functional gene analysis, two dominant members were observed in the microbial dens mat at 70 to 80℃ of hot springs; thermophilic sulfate-reducing Thermodesulfobacteria and thermophilic sulfur-oxidizing Sulfurihydrogenibium. Both members are phylogenetically near to the origin of life. Tracer and incubation experiments using the mat showed that both members contributed to the internal sulfur cycle. These results suggest that the microbial sulfur cycle in the hot spring at 70 to 80℃ is one of ancient types. On the other hand, sulfur-metabolizing bacteria from a moderate-temperature saline and a freshwater lake are phylogenetically affiliated to proteobacteria and more diverse than those from high-temperature terrestrial hot springs. The sulfur cycle and metabolic pathways were complicated as compared to the hot springs. Thus, the process of global temperature decrease on Earth seems to be a key factor for diverse sulfur cycle and the microbial community in aquatic ecosystems.
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