PRELIMINARY ANALYSIS OF E. COLI GENETIC DIVERSITY IN THE GUADALUPE RIVER: INITIAL APPROACH TO FECAL POLLUTION TRACKING

Four sites in the Guadalupe River were sampled for coliform bacteria from the winter 2016 through spring 2017 to assess the microbiological pollution situation in the river and to identify pollution sources. Numbers of putative coliforms detected ranged from below detection limits to 260 CFUs per 100 mL. Over the time period sampled, coliform levels exhibited strong seasonality, probably linked to the amount of rainfall prior to the sampling date. Molecular analysis of confirmed E. coli isolates demonstrated that the spike in coliform numbers 03 December 2016 was dominated by only two unique fingerprints, suggesting the possibility of a watershed source for fecal contamination in the urban area. The diversity of E. coli fingerprints was much greater in the rural portion of the river, suggesting a variety of coliform sources, probably including wildlife. Further studies are needed to identify and manage sources of fecal pollution.