| Project/Area Number |
10490012
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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 |
広領域
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| Research Institution | Ocean Research Institute, University of Tokyo |
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Principal Investigator |
KOGURE Kazuhiro Ocean Research Institute; University of Tokyo, Associate Professor, 海洋研究所, 助教授 (10161895)
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| Co-Investigator(Kenkyū-buntansha) |
NASU Masao Faculty of Pharmaceutical Sciences, Osaka University, Professor, 大学院・薬学系研究科, 教授 (90218040)
CHIURA Hiroshi Division of Natural Sciences, International Christian University. Associate Professor, 教養学部, 助教授 (00103698)
OKAMI Yoshirou Institute of Microbiai Chemistry. Vice Director, 副所長 (90160704)
YAMAMOTO Hiroyuki St. Marianna University School of Medicine, Department of Microbiology, Associate Professor, 医学部, 助教授 (30182645)
MORIYA Tetsuhiro Tokyo Bunka Junior College, Professor, 教授 (10140790)
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥13,000,000 (Direct Cost: ¥13,000,000)
Fiscal Year 1999: ¥5,600,000 (Direct Cost: ¥5,600,000)
Fiscal Year 1998: ¥7,400,000 (Direct Cost: ¥7,400,000)
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| Keywords | Viable but Nonculturable / Stress / Physiological activity / Natural bacterial population / 細菌 / 水界 / 検出 / VBNC |
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| Research Abstract |
Under stressed conditions, some bacteria fall into a physiological state in which cells fail to grow by conventional culture method but still maintain certain metabolic activities. A considerable part of natural bacteria detected under the microscopy are mataintaining metabolic activity, but unable to be cultured. The purpose of the present project is to clarify the physiological basis and ecological implication of so called "viable but nonculturable state" (VNC) of bacteria The results are summarized as follows. First, some bacteria, such as Escherichia coli, Vibrio cholerae, V. parahaemolyticus were placed in the stressed condition and were induced to fall into the VNC state. Biochemical components such as contents of DNA, RNA and protein, and metabolica activities such as respiratory activity or esterase activity were measured. These parameters were analyzed together for contracting models of VNC state. Second, effect of transient temperature up-shift on bacterial cells stressed by low nutrient and low temperature were investigated. It was found that as short as 20 minutes exposure at room temperature was effective to suppress further decrease of viable counts. Conditions affecting this process were checked and molecular basis of this phenomenon has been investigated. Third, distribution and fluctuation of natural bacteiral population that are not detected by conventional culture methods were clarified by the combination of molecular techniques and modern optical devices. In addition, the investigators have made efforts to present and discuss on the issue of VNC phenomenon. It is quite clear that during the last two years, many bacteriologists, biologists and scientists in Japan have been aware of this issue for the first time through the activitis of the members.
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