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Research on physiology and ecology of pathogenic bacteri in viable but nonculturable state

活非培养状态病原菌生理生态学研究

基本信息

批准号：
10490012
负责人：
KOGURE Kazuhiro
金额：
$ 8.32万
依托单位：
Ocean Research Institute, University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10490012/
关键词：
Viable but Nonculturable Stress Physiological activity Natural bacterial population 細菌水界検出 VBNC

项目摘要

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.

在应激条件下，一些细菌陷入生理状态，细胞无法通过常规培养方法生长，但仍保持一定的代谢活动。显微镜下检测到的天然细菌中有相当一部分仍保持代谢活性，但无法培养。本项目的目的是阐明细菌所谓的“存活但不可培养状态”（VNC）的生理基础和生态含义。结果总结如下。首先，将一些细菌，如大肠杆菌、霍乱弧菌、副溶血弧菌置于应激条件下，诱导其进入VNC状态。测量生化成分，例如DNA、RNA和蛋白质的含量，以及代谢活性，例如呼吸活性或酯酶活性。将这些参数一起分析用于 VNC 状态的签约模型。其次，研究了瞬时温度升高对低营养和低温胁迫的细菌细胞的影响。结果发现，在室温下暴露短短20分钟就可以有效抑制活菌数的进一步减少。检查了影响该过程的条件并研究了该现象的分子基础。第三，结合分子技术和现代光学设备，阐明了常规培养方法无法检测到的自然细菌种群的分布和波动。此外，研究者还努力对VNC现象问题进行呈现和讨论。很明显，近两年来，日本的许多细菌学家、生物学家和科学家通过会员的活动首次意识到这个问题。