Preliminary Investigation on the Sterilization of B. subtilis and E. coli Using DBD Plasma

• Main Authors: Yu-jung Chen, 陳郁融
• Other Authors: Moo-been Chang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/50876418544956320689

碩士 === 國立中央大學 === 環境工程研究所 === 99 === How to develop a safe and efficient sterilization method has become an emerging topic in the 21th century. Although conventional methods like heating, ethylene oxide (EtO) or ultraviolet (UV) can achieve good germicidal effect, they are time- and energy-consuming. Compared to conventional methods, nonthermal plasma has been widely used for sterilization of microorganisms not only in food processing, but also in health-care industry. There are many advantages of applying nonthermal plasma for sterilization. In this study, we focus on the germicidal effect of plasma sterlization and the mechanism associated of dielectric barrier discharge (DBD) plasma. Among the parameters investigeted, gas flow patterns would affect sterilization efficiency achieved with DBD and different gas compositions result in different germicidal effect. In single gas plasma, the best germicidal effect is achieved with oxygen. However, addition of oxygen into other working gases also enhances the germicidal effect. The best one is achieved with the gas composition of Ar 75%/O2 25% in mixture. From species analysis, NOγ produced by N2-O2 plasma, as well as O(2D0) and O(5P0) produced by air plasma can oxidize the cell wall of bacteria. SEM and optical microscopy images indicate that samples treated by plasma, ozone results in hydrolysis and oxidation, respectively. Protein and total sugar analysis both show that the degrees of damage to the cell wall caused by different treatment methods vary. The mechanism of cell wall damaged by DBD involves with direct charge bombardment, and then ozone assists the charge to oxidize the cell wall, resulting in rupture.