Study on contribution of shock pressure profiles to inactivation of marine bacteria

在本研究中，我们提出了利用冲击压力灭活海洋细菌的技术，并用物理和生化方法研究了冲击压力作用与海洋细菌灭活之间的关系，以阐明冲击压力对海洋细菌灭活的贡献。为了了解冲击波在容器中的行为，进行了阴影图法可视化实验、压力计压力测量和有限元数值模拟。数值计算结果与实验结果定性和定量吻合。此外，我们还利用几种冲击器、活塞和喷嘴式容器以及容器中的铝制隔膜进行了特征冲击波压力剖面的产生实验。结果，我们成功地产生了持续时间较长的冲击波压力剖面，通常为正冲击波压力，反之亦然。海洋弧菌灭活效果的生物实验。利用特征冲击压力分布图，讨论了冲击压力的直接和间接失活效应。结果表明，在高于400 Mpa左右的压力下，对海洋细菌的动态灭活效果显著，而在较低的冲击压力下，负压产生的自由基的化学灭活效果显著。

In the present study, we proposed the marine bacteria inactivation technology using shock pressure, and investigated the relation between shock pressure action and the inactivation of marine bacteria with physical and biochemical approach in order to clarify the contribution of shock pressure profiles to the inactivation of marine bacteria.We generated shock waves in a water container with a gas gun facility. In order to understand the behavior of shock waves in the container, the visualization experiment with shadowgraph method, the pressure measurement with a filmgauge, and the FEM numerical simulation were executed. The numerical results showed qualitative and quantitative agreements with the experimental results.In addition, we carried out the generation experiment of characteristic shock pressure profiles using several types of impactor; piston and nozzle type container, and an aluminum diaphragm in the container. As a result, we succeeded in generation of the shock pressure profile with long duration, typically positive shock pressure, and vice versa.The bio-experiment for the inactivation effect of a marine Vibrio sp. using the characteristic shock pressure profiles was executed, in order to discuss the direct and indirect inactivation effects of the shock pressure. We obtained the conclusion that dynamic inactivation effect to the marine bacterium arises remarkably at the pressure levels higher than about 400 Mpa, while chemical inactivation effect of the free radical generated by the negative shock pressure can be remarkable at low shock pressure levels.