Department of Civil Engineering, University of Toronto, 35 St. George St., Toronto, Ontario, Canada.
Ground Water. 2011 Jan-Feb;49(1):20-31. doi: 10.1111/j.1745-6584.2010.00690.x.
Understanding the transport behavior, survival, and persistence of pathogens such as Escherichia coli O157:H7 in the subsurface is essential to protection of public health. In this study, the transport of E. coli O157:H7 in a two-dimensional bench-scale sand aquifer system, hereafter referred to as the sandbox, was investigated, with a focus on the impact of biofilm development on E. coli retention and survival. Biofilm growth was initiated through flushing with unsterilized groundwater and addition of glucose, nitrate, and phosphate. Retention of E. coli from an injection test in clean sand, prior to promotion of biofilm growth, was approximately 9%. Subsequent to biofilm growth, 47% of injected E. coli cells were retained under similar flow conditions. After 10 d of no flow, sterile water was flushed through the biofouled sandbox and substantial concentrations (up to 1.5 × 10(5) cells/mL) of E. coli were measured in the effluent indicating that E. coli had survived the starvation period. Confocal laser scanning microscopy revealed that E. coli were located not only on the surface but also within the biofilm. Imposition of starvation conditions resulted in biofilm sloughing and possible mobilization of biofilm-associated E. coli.
了解大肠杆菌 O157:H7 等病原体在地下环境中的迁移行为、存活和持久性对于保护公众健康至关重要。本研究中，我们在二维 bench-scale 砂质含水层系统（简称 sandbox）中研究了大肠杆菌 O157:H7 的迁移情况，重点关注生物膜发育对大肠杆菌保留和存活的影响。通过用未消毒的地下水冲洗并添加葡萄糖、硝酸盐和磷酸盐来启动生物膜生长。在促进生物膜生长之前，从清洁砂中的注射试验中保留的大肠杆菌约为 9%。随后，在类似的流动条件下，注入的大肠杆菌细胞中有 47%被保留下来。在 10 天无流动后，用无菌水冲洗生物污染的 sandbox，在流出物中检测到大量的大肠杆菌（高达 1.5×10(5)细胞/mL），表明大肠杆菌在饥饿期幸存了下来。共聚焦激光扫描显微镜显示，大肠杆菌不仅位于表面，而且还位于生物膜内。施加饥饿条件导致生物膜脱落，并可能使生物膜相关的大肠杆菌发生移动。
