Ran Qinghong, Badgley Brian D, Dillon Nicholas, Dunny Gary M, Sadowsky Michael J
Biotechnology Institute, University of Minnesota, St. Paul, Minnesota, USA.
Appl Environ Microbiol. 2013 May;79(9):3067-75. doi: 10.1128/AEM.03908-12. Epub 2013 Mar 1.
In 2012, the U.S. EPA suggested that coastal and Great Lakes states adopt enterococci as an alternative indicator for the monitoring of recreational water quality. Limited information, however, is available about the presence and persistence of enterococci in Lake Superior. In this study, the density, species composition, and persistence of enterococci in sand, sediment, water, and soil samples were examined at two sites in a Lake Superior watershed from May to September over a 2-year period. The genetic diversity of Enterococcus faecalis isolates collected from environmental samples was also studied by using the horizontal, fluorophore-enhanced repetitive PCR DNA fingerprinting technique. Results obtained by most-probable-number analyses indicated that enterococci were present in 149 (94%) of 159 samples and their densities were generally higher in the summer than in the other months examined. The Enterococcus species composition displayed spatial and temporal changes, with the dominant species being E. hirae, E. faecalis, E. faecium, E. mundtii, and E. casseliflavus. DNA fingerprint analyses indicated that the E. faecalis population in the watershed was genetically diverse and changed spatially and temporally. Moreover, some DNA fingerprints reoccurred over multiple sampling events. Taken together, these results suggest that some enterococci are able to persist and grow in the Lake Superior watershed, especially in soil, for a prolonged time after being introduced.
2012年，美国环境保护局建议沿海和五大湖州采用肠球菌作为监测休闲水质的替代指标。然而，关于苏必利尔湖肠球菌的存在和持久性的信息有限。在本研究中，在两年时间里，于5月至9月对苏必利尔湖流域两个地点的沙子、沉积物、水和土壤样本中的肠球菌密度、物种组成和持久性进行了检测。还使用水平荧光团增强重复PCR DNA指纹技术研究了从环境样本中收集的粪肠球菌分离株的遗传多样性。最大可能数分析结果表明，159个样本中有149个（94%）存在肠球菌，其密度通常在夏季高于其他检测月份。肠球菌的物种组成呈现出空间和时间上的变化，优势物种为海氏肠球菌、粪肠球菌、屎肠球菌、蒙氏肠球菌和黄色肠球菌。DNA指纹分析表明，该流域的粪肠球菌种群在遗传上具有多样性，且在空间和时间上发生变化。此外，一些DNA指纹在多次采样事件中重复出现。综上所述，这些结果表明，一些肠球菌在被引入后能够在苏必利尔湖流域，尤其是在土壤中持续存在并长时间生长。
