| Project/Area Number |
06660241
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
General fisheries
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| Research Institution | KOCHI UNIVERSITY |
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Principal Investigator |
NISHIJIMA Toshitaka Kochi Univ.Faculty of Agriculture, Professor, 農学部, 教授 (60036738)
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| Co-Investigator(Kenkyū-buntansha) |
FUKAMI Kimio Koch Univ.Faculty of Agriculture, Associate Prof., 農学部, 助教授 (30181241)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1994: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Vitamin B_<12> / Vitamin B_<12> binder / Red tide / Phytoplankton / Succession / Growth inhibition / 赤潮藻類 / 回転速度 |
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| Research Abstract |
Ecological roles of vitamin B_<12> binder produced by bacteria and phytoplankton on the growth of red tide phytoplankton were studied. The results were summarized as follows :
1. Red tide phytoplankton, Skeletonema costatum, Gymnodinium mikimotoi, and Heterosigma akashiwo were found to produce vitamin B_<12> binder. H.akashiwo secreted most of the binder produced into the medium, but the others kept ones into their cells.
2. About 60 per cent of total heterotrophic bacteria in seawater was able to produce and excrete B_<12> binder.
3. The B_<12> binder produced by H.akashiwo was found to have a high affinity to free-B_<12> : the dissociation constant was 52.8 ng/l. The binder inhibited non-specifically the growth of phytoplankton requiring free-B_<12> for their growth.
4. In natural eutrophic seawater, B_<12> binders decomposed in parallel with their production. The production of B_<12> binder was due to both bacteria and phytoplankton, while the decomposition was due to bacteria as such.
Present results revealed that B_<12> binder produced by microorganisms could inhibit the growth of B_<12>-requiring phytoplankton and also influence the competition between B_<12>-requirer and the others.
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