| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Monday Sessions |
| Session PS+BI-MoA |
| Session: | Multiphase (Liquid, Solid, Gas) and Biological Related Plasmas |
| Presenter: | Satoshi Kitazaki, Kyushu University, Japan |
| Authors: | S. Kitazaki, Kyushu University, Japan K. Koga, Kyushu University, Japan M. Shiratani, Kyushu University, Japan N. Hayashi, Saga University, Japan |
| Correspondent: | Click to Email |
Nonthermal atmospheric pressure plasmas have been employed for biomedical processing applications, because they provide high density radicals at a low gas temperature [1]. Recently, nonthermal atmospheric pressure plasmas as well as low pressure plasmas have been employed for growth promotion of plant cells [2,3]. In this study, we have developed a scalable atmospheric dielectric barrier discharge (DBD) device for biomedical processing in a large area and have applied the device to growth promotion of bread yeast. The device consisted of 20 electrodes of a stainless rod of 1 mm in outer diameter and 60 mm in length covered with a ceramic tube of 2 mm in outer diameter. The electrodes were arranged parallel with each other at a distance of 0.2 mm. The dry yeast was set at 1 mm under the electrodes. The discharge voltage and frequency were 10 kV and 10 kHz, respectively. The plasma treatment was carried out in the air. The treatment duration Ton was 50, 100 and 150 s. After the treatment, yeast was suspended in 0.5 ml yeast extract peptone dextrose (YPD) medium and agitated with a vortex mixer. 1 μl of sample was mixed with 99 μl YPD medium in a micro well plate and cultivated using a shaking incubator at 30 oC. To obtain growth curve of yeasts time evolution of 660 nm light absorbance of the samples was measured with a micro plate reader. For the control, the absorbance is almost constant until t = 15 hrs after the beginning of the cultivation, which corresponds to the lag phase, and then it exponentially increases with t, the exponential growth phase. For yeast with the plasma treatment, the absorbance increases from t = 0 hrs. At t = 10 hrs, the maximum absorbance for Ton = 150 s is 6.6 times as high as that for the control. From t = 10 to 15 hrs, the gradient of the absorbance becomes gradual. After t = 15 hrs, the absorbance increases exponentially with t. The plasma treatment reduces the lag phase of yeast growth and enhances the growth rate. The growth promotion tends to be enhanced with increasing Ton from 50 to 150 s. The growth promotion, therefore, depends on the dose of radicals produced by discharge plasmas.
[1] M. G. Kong, M. Keidar, and K. Ostrikov, J. Phys. D: Appl. Phys. 44, 174018 (2011).
[2] S. Kitazaki, D. Yamashita, H. Matsuzaki, G. Uchida, K. Koga, and M. Shiratani, Proc. IEEE TENCON 2010, 1960 (2010).
[3] Y. Akiyoshi, A. Nakahigashi, N. Hayashi, S. Kitazaki, T. Iwao, K. Koga, and M. Shiratani, Proc. IEEE TENCON 2010, 1957 (2010).