FECAL CONTAMINATION AND THE PROPORTION OF HUMAN-ASSOCIATED E. coli ALONG NHUE RIVER, VIET NAM

Abstract

According to rapid urbanization in Asian countries, the amount of domestic wastewater discharge has been increasing, resulted in water pollution and potential health risk on human. To secure biological safety of rivers, it is critical to understand the sources of contamination. The present study applied the human-associated E.coli genetic marker (H8) to characterize the source of microbial contamination. E. coli concentration and other pollutants indices were investigated at 10 sites along the river: S1 (upstream) – S10 (downstream). For 220 E. coli isolates collected from river water samples, Real-Time PCR was performed with H8. The results showed that organic pollutants peaked at the middle stream, although they were originally low at upstream (S1). The positive proportion of H8 with E. coli peaked at 40.9 % at middle stream (S6), which was significantly higher than S1 (4.5 %) (p = 0.012). This high proportion implied the relative dominance of human-associated E. coli, which were in line with a large inflow of sanitary wastewater in middle stream, indicated by land use along the river. Thus, we successfully demonstrated the usefulness of H8 to track the source of microbial contamination in the river.