介電質放電對大腸桿菌及枯草芽孢桿菌滅菌效率與機制之初步探討

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

陳郁融(Yu-jung Chen)

指導教授 ： 張木彬

國立中央大學/工學院/環境工程研究所/碩士(2011年)

摘要

如何加快細菌死亡或使其快速失去繁殖能力且不對人體及材料造成危害為現今熱烈討論的研究議題之一。電漿應用於滅菌技術發展至今已有一定成效且與傳統滅菌技術相比，其對材料本身結構無影響也無毒害物質殘留，因此本研究針對介電質放電以放電參數及不同氣體電漿對滅菌效率及滅菌機制進行初步探討，以期開發更安全有效的滅菌技術。首先針對不同放電參數進行探討發現氣流流動方向會影響介電質放電滅菌的殺菌效果。而不同種類的氣體電漿，其殺菌效果也各有不同，本研究以氬氣、氮氣、氧氣及1％四氟甲烷與空氣電漿殺菌效果進行探討，結果為添加如氧氣或四氟甲烷等負電性氣體入氣體電漿系統能提升殺菌效果。以光學放射光譜儀分析物種，空氣電漿中O(2D0)及O(5P0)能與臭氧一同氧化細胞壁，而氮氣 − 氧氣電漿生成氧化力強的NOγ能有效提升殺菌效果。掃描式電子顯微鏡及金相顯微鏡得到滅菌前後的細菌形態，隨著滅菌時間增加其細菌數目隨之減少且細胞壁皆呈現破裂情形，從中了解電漿能將表面細菌以慢燃方式移除，強氧化力的活性物種氧化破壞細菌細胞壁，其細胞壁模糊且變形。蛋白質及總糖分析中發現影響蛋白質釋出量最主要為臭氧等活性物種，影響總糖釋出量為電漿生成的電荷。研究結果中顯示電漿滅菌時生成的電荷與活性物種同時存在且與細菌作用，主要以電荷直接轟擊作用促使電漿區內的細胞壁破裂，而活性物種以氧化作用輔助電漿加速破壞細胞壁，促使細菌水解、死亡。

關鍵字

介電質放電 ； 殺菌效果 ； 滅菌機制 ； 臭氧 ； 總糖及蛋白質釋出量 ； 細胞壁破壞程度

並列摘要

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.

並列關鍵字

Total sugar and protein releasing amount ； Ozone ； Sterilizaiton mechanism ； Germicidal effect ； DBD ； Damage of cell wall

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