Patil S, Moiseev T, Misra N N, Cullen P J, Mosnier J P, Keener K M, Bourke P
School of Food Science and Environmental Health, Dublin Institute of Technology, Dublin, Ireland.
School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Dublin, Ireland.
J Hosp Infect. 2014 Nov;88(3):162-9. doi: 10.1016/j.jhin.2014.08.009. Epub 2014 Sep 19.
Non-thermal plasma has received much attention for elimination of microbial contamination from a range of surfaces.
This study aimed to determine the effect of a range of dielectric barrier discharge high voltage atmospheric cold plasma (HVACP) parameters for inactivation of Bacillus atrophaeus spores inside a sealed package.
A sterile polystyrene Petri dish containing B. atrophaeus spore strip (spore population 2.3 × 10(6)/strip i.e. 6.36 log10/strip) was placed in a sealed polypropylene container and was subjected to HVACP treatment. The HVACP discharge was generated between two aluminium plate electrodes using a high voltage of 70kVRMS. The effects of process parameters, including treatment time, mode of exposure (direct/indirect), and working gas types, were evaluated. The influence of relative humidity on HVACP inactivation efficacy was also assessed. The inactivation efficacy was evaluated using colony counts. Optical absorption spectroscopy (OAS) was used to assess gas composition following HVACP exposure.
A strong effect of process parameters on inactivation was observed. Direct plasma exposure for 60s resulted in ≥6 log10 cycle reduction of spores in all gas types tested. However, indirect exposure for 60s resulted in either 2.1 or 6.3 log10 cycle reduction of spores depending on gas types used for HVACP generation. The relative humidity (RH) was a critical factor in bacterial spore inactivation by HVACP, where a major role of plasma-generated species other than ozone was noted. Direct and indirect HVACP exposure for 60s at 70% RH recorded 6.3 and 5.7 log10 cycle reduction of spores, respectively.
In summary, a strong influence of process parameters on spore inactivation was noted. Rapid in-package HVACP inactivation of bacterial spores within 30-60s demonstrates the promising potential application for reduction of spores on medical devices and heat-sensitive materials.
非热等离子体在消除各种表面的微生物污染方面备受关注。
本研究旨在确定一系列介质阻挡放电高压大气冷等离子体（HVACP）参数对密封包装内萎缩芽孢杆菌孢子灭活的影响。
将含有萎缩芽孢杆菌孢子条（孢子数量为2.3×10⁶/条，即6.36 log₁₀/条）的无菌聚苯乙烯培养皿置于密封的聚丙烯容器中，并进行HVACP处理。使用70kVRMS的高压在两个铝板电极之间产生HVACP放电。评估了包括处理时间、暴露模式（直接/间接）和工作气体类型等工艺参数的影响。还评估了相对湿度对HVACP灭活效果的影响。使用菌落计数评估灭活效果。在HVACP暴露后，使用光吸收光谱法（OAS）评估气体成分。
观察到工艺参数对灭活有显著影响。在所有测试气体类型中，直接等离子体暴露60秒导致孢子减少≥6 log₁₀周期。然而，根据用于产生HVACP的气体类型，间接暴露60秒导致孢子减少2.1或6.3 log₁₀周期。相对湿度（RH）是HVACP灭活细菌孢子的关键因素，其中注意到除臭氧外等离子体产生的物质起主要作用。在70%相对湿度下直接和间接HVACP暴露60秒分别记录到孢子减少6.3和5.7 log₁₀周期。
总之，注意到工艺参数对孢子灭活有强烈影响。在30 - 60秒内对包装内细菌孢子进行快速HVACP灭活证明了其在减少医疗设备和热敏材料上的孢子方面具有潜在的应用前景。
