Cushnie T P Tim, Robertson Peter K J, Officer Simon, Pollard Pat M, McCullagh Cathy, Robertson Jeanette M C
Centre for Research in Energy and the Environment, The Robert Gordon University, Schoolhill, Aberdeen, United Kingdom.
Chemosphere. 2009 Mar;74(10):1374-8. doi: 10.1016/j.chemosphere.2008.11.012. Epub 2008 Dec 19.
The current study sought to assess the importance of three common variables on the outcome of TiO(2) photocatalysis experiments with bacteria. Factors considered were (a) ability of test species to withstand osmotic pressure, (b) incubation period of agar plates used for colony counts following photocatalysis and (c) chemical nature of suspension medium used for bacteria and TiO(2). Staphylococcus aureus, Escherichia coli, Salmonella ser. Typhimurium and Pseudomonas aeruginosa were found to vary greatly in their ability to withstand osmotic pressure, raising the possibility that osmotic lysis may be contributing to loss of viability in some photocatalytic disinfection studies. Agar plate incubation time was also found to influence results, as bacteria treated with UV light only grew more slowly than those treated with a combination of UV and TiO(2.) The chemical nature of the suspension medium used was found to have a particularly pronounced effect upon results. Greatest antibacterial activity was detected when aqueous sodium chloride solution was utilised, with approximately 1 x 10(6) CFU mL(-1)S. aureus being completely killed after 60 min. Moderate activity was observed when distilled water was employed with bacteria being killed after 2h and 30 min, and no antibacterial activity at all was detected when aqueous tryptone solution was used. Interestingly, the antibacterial activity of UV light on its own appeared to be very much reduced in experiments where aqueous sodium chloride was employed instead of distilled water.
本研究旨在评估三个常见变量对TiO₂光催化细菌实验结果的重要性。所考虑的因素包括：(a)受试菌种耐受渗透压的能力；(b)光催化后用于菌落计数的琼脂平板的培养时间；(c)用于细菌和TiO₂的悬浮培养基的化学性质。结果发现，金黄色葡萄球菌、大肠杆菌、鼠伤寒沙门氏菌和铜绿假单胞菌在耐受渗透压的能力上差异很大，这增加了在一些光催化消毒研究中渗透裂解可能导致活力丧失的可能性。还发现琼脂平板培养时间会影响结果，因为仅用紫外线处理的细菌比用紫外线和TiO₂联合处理的细菌生长得更慢。所用悬浮培养基的化学性质对结果有特别显著的影响。当使用氯化钠水溶液时检测到最大抗菌活性，60分钟后约1×10⁶CFU/mL的金黄色葡萄球菌被完全杀死。当使用蒸馏水时观察到中等活性，细菌在2小时30分钟后被杀死，而当使用胰蛋白胨水溶液时未检测到任何抗菌活性。有趣的是，在使用氯化钠水溶液而非蒸馏水的实验中，紫外线自身的抗菌活性似乎大大降低。
