Negrón-Talavera, Ginamary

Profile Picture

Filters

20151
Reset filters

Settings

Citations

Publication Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    Publication
    Monitoring the diversity and species distribution of enterococci at a subtropical seawater system in Mayagüez, Puerto Rico
    (2015) Negrón-Talavera, Ginamary; Ríos-Hernández, Luis A.; College of Arts and Sciences - Sciences; Rodríguez-Minguela, Carlos; Santos-Flores, Carlos J.; Department of Biology; Sotomayor-Ramírez, David
    Enterococci are an important group of bacteria used as fecal indicator by the United States Environmental Protection Agency (USEPA) to evaluate the quality of recreational waters. Specifically, a beach is “contaminated” when the enterococci concentrations exceed the guideline of 104 CFU/100ml in a single sample analysis. Unfortunately, this method only provides numerical information and it lacks the differentiation of species and contamination sources. Given the establishment of this guideline in non-tropical regions and, due the frequent exceedance in tropical environments, we hypothesize that the USEPA enterococci guideline is not a reliable method to monitor the quality of recreational waters in Puerto Rico. In order to confirm this, first, we developed a new enterococci species identification method capable of discriminating adequately among environmental isolates using the RFLP technique of the atpA 1,102-bp fragment amplification. Then, this method was combined with a biochemical screening to confirm the isolates as Enterococcus and monitor the community in a beach water system every 4 hours for 24 hours. Even though our newly developed method has a limitation identifying E. casseliflavus isolates, we were able to identify non-pigmented enterococci species. It should be noted that three enterococci species were consistently identified: E. faecalis, E. faecium and E. gallinarum. Interestingly, our findings in the 24-hour study showed that the diversity of enterococci in the beach water system was principally limited to E. faecalis, E. faecium, E. gallinarum, E. casseliflavus and other unknown species. These enterococci species were also identified during the “recent fecal contamination event” (before, during, and after), including the presence of five virulence factors (gelE, asa1, hyl, esp, and cylA) to compare the genetic makeup of the same enterococci species that were identified through the event. However, the presence of five virulence genes, limited to E. faecalis and E. faecium, had no significant variation when the enterococci concentrations exceeded, or not, the USEPA standard. Our results showed that the enterococci community was extremely dynamic, acquiring and losing species diversity before, during, and after an exceedance event. If we consider our overall results, we might suggest that those exceedance events are not necessarily by a recent fecal contamination event. Finally, although further studies are needed to determine the source of enterococci introduction, fecal or not, we have to conclude that a single numerical datum is not a reliable method to identify the potential of health risks by fecal contamination in a tropical recreational water system.