Development of an experimental system for cell viability assays of yeasts using gas-temperature controllable plasma jets*

When model organisms such as fission yeast and budding yeast are treated by direct plasma irradiation, it is essential to maintain the irradiated target at an appropriate temperature. Therefore, we have developed a room temperature atmospheric pressure helium plasma jet device utilizing a Peltier element to cool the feeding gas [1]. Here we report on the realization of an experimental system for cell viability assays of yeasts using this device. Good reproducibility of cell viability was observed when gas temperature, gas flow rate, applied high voltage, and irradiation distance remained fixed, and only irradiation time was used as a parameter. This allows for a variety of experiments, such as the search for plasma-resistant mutants that will contribute to the identification of genes involved in resistance to direct plasma irradiation. Details of this system, including the density of ground-state oxygen atoms in the plasma plume that was measured by vacuum ultraviolet absorption spectroscopy, the molar concentration of hydrogen peroxide produced upon irradiation to the culture medium, and the time development of medium temperature during plasma irradiation, will be reported at the conference.

[1] S. Yoshimura et al., Jpn. J. Appl. Phys. 58, SEEG03 (2019).