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. | Vietnam Journal of Science and Technology 56 (2C) (2018) 16-22 FECAL CONTAMINATION AND THE PROPORTION OF HUMAN-ASSOCIATED E. coli ALONG NHUE RIVER, VIET NAM Mai Tanaka1, Hidenori Harada1, *, Shigeo Fujii1, Min Li Chua1, Nguyen Duy Hung2 Nguyen Pham Hong Lien2, Nghiem Trung Dung2, Ryota Gomi3 1 2 Graduate School of Global Environmental Studies, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 JAPAN School of Environmental Science and Technology, Hanoi University of Science and Technology, 1 Dai Co Viet Road, Ha Noi, Viet Nam 3 Graduate School of Engineering, Kyoto University, Kyoto daigaku-katsura, Nishikyo-ku, Kyoto 615-8530 JAPAN * Email: Received: 10 May 2018; Accepted for publication: 20 August 2018 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 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 % at middle stream (S6), which was significantly higher than S1 ( %) (p = ). 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 .
