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

本文提出了利用冲击压力灭活海洋细菌的技术，并通过物理和生物化学方法研究了冲击压力作用与海洋细菌灭活的关系，以阐明冲击压力剖面对海洋细菌灭活的贡献。为了了解冲击波在容器中的行为，采用阴影法进行了可视化实验，采用薄膜压力计进行了压力测量，并进行了有限元数值模拟。数值计算结果与实验结果在定性和定量上都吻合较好。此外，我们还利用几种类型的冲击器、活塞和喷嘴式容器以及容器中的铝膜片进行了特征冲击压力剖面的生成实验。结果表明，该冲击压力曲线具有较长的持续时间，典型的正冲击压力，反之亦然。利用该特征冲击压力曲线对一种海洋弧菌的灭活效果进行了生物实验，探讨了冲击压力的直接和间接灭活效果。结果表明，当压力高于400 Mpa时，对海洋细菌的动力学灭活效果显著，而当压力较低时，由负冲击压力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.