Assessment of enterococci species distribution in a subbasin of the Lajas Valley using molecular techniques
CollegeCollege of Agricultural Sciences
DepartmentDepartment of Crops and Agro-Environmental Sciences
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A common biological parameter for assessing the quality of a waterbody is the presence of fecal bacteria. Within the fecal bacteria group there are specific bacterial genres such as enterococci which are associated with the gastrointestinal tract of warm blooded animals. Various enterococci species are related to specific host organisms and the identification of enterococci to the species level can be used to presumably track down their source. The aim of this study was to use molecular techniques to identify the diversity and abundance of four main enterococci species in order to assess bacterial contributions in the “Mondongo Creek” located in the Lajas Valley, Puerto Rico. Five samplings were carried out from January 2017 to January 2018, upstream and downstream of the waste water treatment plant (WWTP) discharge. High concentrations of enterococci populations were found throughout the creek, both before and after the WWTP effluent outfall. These high concentrations of enterococci were assessed with specific molecular markers to distinguish among E. faecalis, E. faecium, E. casseliflavus and E. gallinarum, and to determine if they were caused by contributions from the WWTP. Enterococci concentrations before and after the WWTP effluent outfall showed that these did not increase significantly. With respect to individual species’ abundance minor fluctuations were observed downstream, but no significant difference was found in the abundance of the three main species detected before and after the WWTP effluent outfall. I conclude that the WWTP does not contribute significant enterococci concentrations nor affects species abundance downstream in this waterbody.