1991 Fiscal Year Final Research Report Summary
Thermal Regulation of Aerobic and Anaerobic Synthesis of Unsaturated Fatty Acid.
| Project/Area Number |
02640516
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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 |
植物生理学
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| Research Institution | Hokkaido University |
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Principal Investigator |
FUKUNAGA Noriyuki Science, Biology, Ass. Professor., 理学部, 助教授 (30113616)
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| Co-Investigator(Kenkyū-buntansha) |
TAKADA Yasuhiro Science, Biology, Lecturer., 理学部, 講師 (10163213)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Desaturase / Auxotrophic mutant / Unsaturated fatty acid / Membrane lipid / Aerobic synthesis / Anaerobic synthesis / Psychrotroph / Low temperature |
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| Research Abstract |
Unsaturated fatty acid auxotorophic mutant was isolated from a psychrotrophic bacterium, PseudoNonas sp. strain E-3, which possess two different mechanisms for unsaturated fatty acid. In order to characterize the mutant, physiological and biochemical studies were carried out.
(1)Growth rate and bacterial mass of the mutant was dependent on the concentration of added unsaturated fatty acid(e. g. palmitoleic or oleic acid)in medium, and the mutant showed almost the same growth rate to that of the parent strain when 0.01% oleic acid was added in the medium.
(2)Oleic acid was found to be a major unsaturated fatty acid component in the phospholipid from the mutant strain grown on the medium containing oleic acid. On the other hand, cis-vaccenic acid but not oleic-acid was a major unsaturated fatty acid in the parent strain grown under the same condition. It was found that the fatty acid composition of the phospholipid from the parent strain was independent on exogenously added unsaturated fatty acid.
(3)Anaerobic synthesis of unsaturated fatty acid was compared between in vitro reactions by the fatty acid syntheses prepared from the mutant and parent strains. Amounts of unsaturated fatty acids synthesized from radio-labeled precursor were found to be almost the same in the both strains.
(4)The activity of the fatty acid desaturase, the key enzyme in the aerobic mechanism, in the mutant strain was less than a half of that of the parent strain. Furthermore, the enzyme activity could not be induced in the mutant strain, when the cells were cultured in the medium comprised of peptone and saturated fatty acid.
(5)The mutant strain exhibited much higher sensitivity to 3-decynoyl-Ncysteamine, an inhibitor of the anaerobic pathway, than the parent strain. Above results indicate that the both aerobic and anaerobic pathways are required for the growth of Pseudomonas E-3.
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