| Project/Area Number |
15380065
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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 |
Applied microbiology
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
SHIMODA Mitsuya Kyushu university, Department of Bioscience and Biotechnology, Professor, 農学研究院, 教授 (70149871)
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| Co-Investigator(Kenkyū-buntansha) |
IGURA Noriyuki Kyushu university, Department of Bioscience and Biotechnology, Associate Professor, 農学研究院, 助教授 (30260722)
早川 功 九州大学, 大学院・農学研究院, 教授 (30038252)
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| Project Period (FY) |
2003 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥15,900,000 (Direct Cost: ¥15,900,000)
Fiscal Year 2005: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2004: ¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2003: ¥9,200,000 (Direct Cost: ¥9,200,000)
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| Keywords | carbon dioxide / high-pressure carbonation / non-thermal microbial inactivation / non-thermal enzyme inactivation / 細胞内pH / カーボネーションバイオリアクター / 加圧カーボネーション殺菌 |
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| Research Abstract |
Under high-pressure carbonation, the cells of S.cerevisiae will arrest the activities of electron-transfer chains since carbonation completely expels dissolved O_2. Consequently, the reduction of pHi will activate the proton-translocating plasma membrane H^+-ATPase. It is believed that the quantity of protons pumped out is correlated to the decrease in ATP_<per cell>. Therefore, the time-courses of viability loss and ATP decrease were investigated in physiological saline with and without DCCD to investigate the role of plasma membrane H^+-ATPase.
In the absence of DCCD, ATP_<per cell> decreased to less than 10% in the first 2 min and almost disappeared within the next 5 min. Such depletion of ATP_<per cell> causes dissipation of the proton motive force across the plasma membrane. The time courses of viability loss and decrease of ATP_<per cell> in the absence of DCCD showed that the cells began to lose their viability immediately after the ATP depletion. When the concentration of DCCD a
… More
dded was increased, the kinetics of cell death was accelerated, although the ATP_<per cell> was preserved. In the presence of 10 μM DCCD, the cells were killed immediately. The slope of the survivor curve was almost the same as that in the system without DCCD. This suggests that the reduction in pHi was almost the same in the presence and absence of DCCD. In the systems which included DCCD at a concentration > 50 μM, the cells were killed immediately after the start of carbonation. These results suggest that the pHi reduction was correlated to the inhibition ratio of the plasma membrane H^+-ATPase. That is, both the depletion of cellular ATP and the addition of DCCD could arrest the plasma membrane H^+-ATPase, proton pump, but there was a difference in the amounts of HCO_3^- ions stored in the cells in the two systems. Since the larger the consumption of ATP_<per cell>, the larger the amount of HCO_3^- ion stored in the cytoplasm, the pHi reduction was considered to be more significant in the system with DCCD. It was found that plasma membrane H^+-ATPase was able to preserve the cells from the reduction of pHi, provided that the cells had sufficient levels of ATP. In fact, there was a lag-time, presumably due to a period of consumption of cellular ATP between the start of carbonation and viability loss. Less
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