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Open Access

Open Access


Bacterial source tracking was used to identify sources of fecal contamination in a constructed wetland. Nucleotide sequence differences in the Escherichia coli malate dehydrogenase (mdh) gene were used to distinguish between strains isolated from pigeon and cattle feces. Fourteen E. coli isolates were taken from cattle and pigeon fecal samples and sixteen E. coli isolates were taken from wetland water samples. A region of the E. coli mdh gene was amplified via PCR and sequenced. Twelve distinct sequences were obtained. Water samples indicated the presence of both pigeon and cattle fecal contamination in the wetland. Six sequences distinct from those isolated from pigeon and cattle feces also were present. Three of these sequences were pigeon-specific and two were cattle-specific. The presence of host-specific sequences indicates that sequence-based source tracking methods show promise for identifying fecal contamination.