Bosshard Franziska, Berney Michael, Scheifele Michael, Weilenmann Hans-Ulrich, Egli Thomas
Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, 8092 Zürich, Switzerland.
Eawag, Swiss Federal Institute of Aquatic Science and Technology, PO Box 611, CH-8600 Dübendorf, Switzerland.
Microbiology (Reading). 2009 Apr;155(Pt 4):1310-1317. doi: 10.1099/mic.0.024794-0.
Pathogenic enteric bacteria are a major cause of drinking water related morbidity and mortality in developing countries. Solar disinfection (SODIS) is an effective means to fight this problem. In the present study, SODIS of two important enteric pathogens, Shigella flexneri and Salmonella typhimurium, was investigated with a variety of viability indicators including cellular ATP levels, efflux pump activity, glucose uptake ability, and polarization and integrity of the cytoplasmic membrane. The respiratory chain of enteric bacteria was identified to be a likely target of sunlight and UVA irradiation. Furthermore, during dark storage after irradiation, the physiological state of the bacterial cells continued to deteriorate even in the absence of irradiation: apparently the cells were unable to repair damage. This strongly suggests that for S. typhimurium and Sh. flexneri, a relatively small light dose is enough to irreversibly damage the cells and that storage of bottles after irradiation does not allow regrowth of inactivated bacterial cells. In addition, we show that light dose reciprocity is an important issue when using simulated sunlight. At high irradiation intensities (>700 W m(-2)) light dose reciprocity failed and resulted in an overestimation of the effect, whereas reciprocity applied well around natural sunlight intensity (<400 W m(-2)).
致病性肠道细菌是发展中国家与饮用水相关的发病和死亡的主要原因。太阳能消毒（SODIS）是解决这一问题的有效手段。在本研究中，利用包括细胞ATP水平、外排泵活性、葡萄糖摄取能力以及细胞质膜的极化和完整性等多种活力指标，对两种重要的肠道病原体——福氏志贺菌和鼠伤寒沙门氏菌进行了太阳能消毒研究。已确定肠道细菌的呼吸链可能是阳光和紫外线A照射的靶点。此外，在照射后的黑暗储存期间，即使在没有照射的情况下，细菌细胞的生理状态仍继续恶化：显然细胞无法修复损伤。这有力地表明，对于鼠伤寒沙门氏菌和福氏志贺菌，相对较小的光照剂量就足以不可逆地损伤细胞，并且照射后瓶子的储存不会使失活的细菌细胞重新生长。此外，我们表明，在使用模拟阳光时，光剂量等效性是一个重要问题。在高辐照强度（>700 W m(-2)）下，光剂量等效性不成立，导致对效果的高估，而在自然阳光强度（<400 W m(-2)）左右，等效性适用良好。
