Microorganism inactivation using high-pressure generation in sealed vessels under sub-zero temperature

In order to test the possibility of utilizing high pressure in bioscience and biotechnology, a simple high pressure generation method and its use for microbial inactivation have been studied. When a pressure vessel was filled with water, sealed tightly and cooled to sub-zero temperature, high pressure was generated in the vessel. The maximum pressure generation was 206 MPa at -23 °C. The high pressure generated was effective at inactivating microorganisms: yeast (Saccharomyces cerevisiae and Zygosaccharomyces rouxii), bacteria (Lactobacillus brevis and Eschericia coli), fungi (Aspergillus niger and Aspergillus oryzae) were completely inactivated by storing the sealed vessels containing these microorganisms at -20 °C for 24h. However, Staphylococcus aureus was only partly inactivated under the same conditions. This method opens up a new application of high pressure for storing, transporting, and sterilizing of foods and biological materials.