Temporal Variability of Genetic Patterns of Fecal Indicator Bacteria Collected from a Fixed Point in the River

By applying pulsed-field gel electrophoresis（PFGE）to the aquatic environment as a source tracking method of fecal pollution, the temporal variability of genetic patterns of Enterococcus faecium, as fecal indicator bacterium, was examined. Surface water samples were collected from a fixed point of the Miyazaki municipal river during a two-month period. E. faecium strains were identified and collected from each water sample.Genotypes（PFGE types）of all E. faecium strains were analyzed by PFGE. Then, the similarities between the PFGE types obtained from the first day and those from the other days were compared using dendrogram analysis. The PFGE type of E. faecium was not significantly changed for the initial three days. After the seventh day, the dominant PFGE types were changed. The PFGE types of the 30th and 60th days were not very similar to those of the first day. It was indicated that genetic patterns of E. faecium might change to completely dissimilar patterns in a fixed point of the municipal river. Therefore, it is very important to consider the temporal variability of genetic pattern of fecal indicator bacteria for source tracking of fecal pollution.