Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA.
Environ Microbiol. 2013 Feb;15(2):517-26. doi: 10.1111/j.1462-2920.2012.02877.x. Epub 2012 Sep 26.
The role of fecal indicator bacteria (FIB) in water quality assessment is to provide a warning of the increased risk of pathogen presence. An effective surrogate for waterborne pathogens would have similar survival characteristics in aquatic environments. Although the effect of abiotic factors such as sunlight and salinity on the survival of FIB and pathogens are becoming better understood, the effect of the indigenous microbiota is not well characterized. The influence of biotic factors on the survival of non-pathogenic Escherichia coli, Enterococcus faecalis, and E. coli O157:H7 were compared in fresh (river) water and sediments over 5 days. Treatments were (i) disinfection (filtration of water and baking of sediments) to remove indigenous protozoa (predators) and bacteria (competitors), and (ii) kanamycin treatment to reduce competition from indigenous bacteria. The disinfection treatment significantly increased survival of E. coli, E. coli O157:H7 and Ent. faecalis in the water column. In sediments, survival of FIB but not that of E. coli O157:H7 increased in disinfected treatments, indicating that the pathogen's survival was unaffected by the natural microbiota. Location (water or sediment) influenced bacterial survival more than species/type in the disinfection experiment. In the competition experiments where only the natural bacterial flora was manipulated, the addition of kanamycin did not affect the survival of Ent. faecalis, but resulted in greater survival of E. coli in water and sediment. Species/type influenced survival more than the level of competition in this experiment. This study demonstrates the complexity of interactions of FIB and pathogens with indigenous microbiota and location in aquatic habitats, and argues against over-generalizing conclusions derived from experiments restricted to a particular organism or habitat.
粪便指示菌（FIB）在水质评估中的作用是提供病原体存在风险增加的警告。一种有效的水生病原体替代物在水生环境中的生存特征应该相似。尽管非生物因素（如阳光和盐度）对 FIB 和病原体存活的影响越来越被理解，但本土微生物群落的影响还没有很好地描述。在 5 天的时间里，比较了新鲜（河流）水和沉积物中，非致病性大肠杆菌、粪肠球菌和大肠杆菌 O157:H7 受生物因素影响的存活情况。处理方法是（i）消毒（过滤水和烘烤沉积物）以去除本土原生动物（捕食者）和细菌（竞争者），和（ii）卡那霉素处理以减少来自本土细菌的竞争。消毒处理显著增加了水中大肠杆菌、大肠杆菌 O157:H7 和粪肠球菌的存活。在沉积物中，FIB 的存活增加，但大肠杆菌 O157:H7 的存活没有增加，表明病原体的存活不受自然微生物群落的影响。在消毒实验中，位置（水或沉积物）对细菌存活的影响大于物种/类型。在仅操纵自然细菌菌群的竞争实验中，添加卡那霉素不会影响粪肠球菌的存活，但会导致水中和沉积物中大肠杆菌的存活增加。在这个实验中，物种/类型比竞争水平更能影响存活。本研究表明 FIB 和病原体与本土微生物群落和水生栖息地位置的相互作用的复杂性，并反对从仅限于特定生物体或栖息地的实验中得出过于笼统的结论。
