Affiliation:
1. College of Medical Technology, Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 310053, China
2. Department of Biological Sciences, University of Wisconsin-Milwaukee 53211, U.S.A
3. College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, Zhejiang, 310058, China
Abstract
Abstract
Bacteria, especially pathogenic bacteria, were detected in order to estimate the safety of drinking water distribution systems (DWDS). 16 biofilms and 12 water samples (6 retained and 6 flowing) were collected from a city DWDS in Eastern China. Biofilms were observed using scanning electron microscopy. Cultivable bacteria of biofilms were counted by heterotrophic plate counts, ranging from 3.61 × 101 to 1.67 × 106 CFU·cm−2. Coliforms, Salmonella, Shigella, Vibrio, and Legionella were separated by EMB agar, Salmonella chromogenic medium, Shigella chromogenic medium, TCBS agar, BCYE agar, and 13/16, 8/16, 7/16, 6/16, 0/16 biofilm samples were found positive respectively. Retained and flowing water samples were collected to estimate the influence of hydrodynamic conditions on biofilm detachment. All 6 retained water samples were positive for bacteria, count ranged from 1.2 × 103 to 2.8 × 104 CFU·mL−1 and 2/6, 3/6, 2/6, 0/6, 0/6 samples were positive for coliforms, Salmonella, Shigella, Legionella, and Vibrio, respectively. While only 3 of 6 flowing water samples were bacteria positive, counts ranged from 102 to 103 CFU·mL−1, 2/6 were coliforms positive, no pathogens under testing were detected. The results show that there are pathogens in DWDS biofilms, which can cause health related problems if detached from their surface.
Publisher
Oxford University Press (OUP)
Subject
Genetics,Molecular Biology,Microbiology