Korajkic Asja, McMinn Brian R, Shanks Orin C, Sivaganesan Mano, Fout G Shay, Ashbolt Nicholas J
National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA
National Exposure Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Cincinnati, Ohio, USA.
Appl Environ Microbiol. 2014 Jul;80(13):3952-61. doi: 10.1128/AEM.00388-14. Epub 2014 Apr 18.
The sanitary quality of recreational waters that may be impacted by sewage is assessed by enumerating fecal indicator bacteria (FIB) (Escherichia coli and enterococci); these organisms are found in the gastrointestinal tracts of humans and many other animals, and hence their presence provides no information about the pollution source. Microbial source tracking (MST) methods can discriminate between different pollution sources, providing critical information to water quality managers, but relatively little is known about factors influencing the decay of FIB and MST genetic markers following release into aquatic environments. An in situ mesocosm was deployed at a temperate recreational beach in the Mississippi River to evaluate the effects of ambient sunlight and biotic interactions (predation, competition, and viral lysis) on the decay of culture-based FIB, as well as molecularly based FIB (Entero1a and GenBac3) and human-associated MST genetic markers (HF183 and HumM2) measured by quantitative real-time PCR (qPCR). In general, culturable FIB decayed the fastest, while molecularly based FIB and human-associated genetic markers decayed more slowly. There was a strong correlation between the decay of molecularly based FIB and that of human-associated genetic markers (r(2), 0.96 to 0.98; P < 0.0001) but not between culturable FIB and any qPCR measurement. Overall, exposure to ambient sunlight may be an important factor in the early-stage decay dynamics but generally was not after continued exposure (i.e., after 120 h), when biotic interactions tended to be the only/major influential determinant of persistence.
通过对粪便指示菌（FIB）（大肠杆菌和肠球菌）进行计数，来评估可能受污水影响的娱乐用水的卫生质量；这些微生物存在于人类和许多其他动物的胃肠道中，因此它们的存在并不能提供有关污染源的信息。微生物源追踪（MST）方法可以区分不同的污染源，为水质管理人员提供关键信息，但对于FIB和MST基因标记物释放到水生环境后的衰减影响因素，人们了解得相对较少。在密西西比河的一个温带娱乐海滩部署了一个原位中宇宙，以评估环境阳光和生物相互作用（捕食、竞争和病毒裂解）对基于培养的FIB、以及通过定量实时PCR（qPCR）测量的基于分子的FIB（Entero1a和GenBac3）和人类相关MST基因标记物（HF183和HumM2）衰减的影响。一般来说，可培养的FIB衰减最快，而基于分子的FIB和人类相关基因标记物衰减较慢。基于分子的FIB衰减与人类相关基因标记物衰减之间存在很强的相关性（r(2)，0.96至0.98；P < 0.0001），但可培养的FIB与任何qPCR测量值之间不存在相关性。总体而言，暴露于环境阳光可能是早期衰减动态中的一个重要因素，但在持续暴露后（即120小时后）通常不是，此时生物相互作用往往是持久性的唯一/主要影响决定因素。
