Hwang Myoung Goo, Katayama Hiroyuki, Ohgaki Shinichiro
Department of Urban Engineering, The University of Tokyo, 7-3-1 Hongo Bunkyo, Tokyo 113-8656, Japan.
Water Res. 2007 Oct;41(18):4097-104. doi: 10.1016/j.watres.2007.05.052. Epub 2007 Jun 3.
In this study, silver cations dissolved as silver nitrate at various concentrations were exposed to Legionella pneumophila, Pseudomonas aeruginosa, and Escherichia coli to quantitatively estimate the bactericidal ability of silver. Observed data were analyzed using a newly developed model (Cs x T) that introduced a specific amount of chemisorbed silver onto a bacterial cell (Cs), which represented the chemisorption properties of silver on the bacterial cell body. Silver cations were rapidly chemisorbed onto bacterial cells after injection into samples, and Cs values (initial concentration of silver was 0.1 mg Ag/l) were calculated as 1.810 x 10(-6) (L. pneumophila), 1.102 x 10(-6) (P. aeruginosa), and 1.638 x 10(-6) microg Ag/cell(i) (E. coli) after incubation for 8 h. During that time, the three tested bacteria were completely inactivated under the detection limit (>7.2 log reduction). Based on the calculated Cs values, bacterial tolerance against silver was estimated by using the equation (Cs x T) multiplying the Cs values with exposure time (T). The Cs x T values well represented the bactericidal abilities of silver against the tested bacteria. The demanded Cs x T values to accomplish a 1 log inactivation (90% reduction) of L. pneumophila, P. aeruginosa, and E. coli (the initial numbers of bacteria were 1.5 x 10(7) CFU/ml, approximately) were estimated as 2.44 x 10(-6), 0.63 x 10(-6), and 0.46 x 10(-6) microgh/cell(i) of silver. The values were significantly reduced to 1.54 x 10(-6), 0.31 x 10(-6), and 0.25 x 10(-6) microgh/cell(i), respectively, with simultaneous injection of silver and copper. This study shows the successful quantitative estimation of the bactericidal ability of silver by applying the newly developed model (Cs x T). Among the tested bacteria, L. pneumophila showed the strongest tolerance to exposure of the same concentration of silver.
在本研究中，将以不同浓度溶解为硝酸银的银阳离子暴露于嗜肺军团菌、铜绿假单胞菌和大肠杆菌，以定量评估银的杀菌能力。使用新开发的模型（Cs×T）对观测数据进行分析，该模型引入了细菌细胞上化学吸附银的特定量（Cs），它代表了银在细菌细胞体上的化学吸附特性。银阳离子注入样品后迅速化学吸附到细菌细胞上，孵育8小时后，计算得到的Cs值（银的初始浓度为0.1mg Ag/l）分别为嗜肺军团菌1.810×10⁻⁶、铜绿假单胞菌1.102×10⁻⁶和大肠杆菌1.638×10⁻⁶μg Ag/细胞（i）。在此期间，三种受试细菌在检测限以下完全失活（>7.2个对数级减少）。根据计算得到的Cs值，通过将Cs值与暴露时间（T）相乘的方程（Cs×T）来估计细菌对银的耐受性。Cs×T值很好地代表了银对受试细菌的杀菌能力。使嗜肺军团菌、铜绿假单胞菌和大肠杆菌（初始细菌数量约为1.5×10⁷CFU/ml）实现1个对数级失活（减少90%）所需的Cs×T值估计分别为2.44×10⁻⁶、0.63×10⁻⁶和0.46×10⁻⁶μg h/细胞（i）银。同时注入银和铜时，这些值分别显著降低至1.54×10⁻⁶、0.31×10⁻⁶和0.25×10⁻⁶μg h/细胞（i）。本研究表明，通过应用新开发的模型（Cs×T）成功地对银的杀菌能力进行了定量评估。在受试细菌中，嗜肺军团菌对相同浓度银的暴露表现出最强的耐受性。
