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Comparison of Cultural and Molecular Fecal Indicator Measurements in Surface Water and Periphyton Biofilms in Artificial Streams
Citation:
PEED, L., C. A. KELTY, M. SIVAGANESAN, T. Mooney, C. T. NIETCH, AND O. C. SHANKS. Comparison of Cultural and Molecular Fecal Indicator Measurements in Surface Water and Periphyton Biofilms in Artificial Streams . Presented at American Society of Microbiology 112th General Meeting, San Francisco, CA, June 16 - 19, 2012.
Impact/Purpose:
To inform the public.
Description:
Studies suggest that periphyton in streambeds can harbor fecal indicator bacteria (FIB) and, under certain circumstances, can be transferred from the periphyton biofilm into the surface water. An indoor mesocosm study was conducted at the U.S. Environmental Protection Agency Experimental Stream Facility in Milford, OH to explore potential relationships between periphyton, water quality, and storm hydrology. The experiment was conducted over a 26 week period and organized into three phases: 1) a colonization period, 2) a wastewater loading period, and 3) a recovery period. In each phase eight mesocosms, configured in two banks of four each, were linked in series in an upstream –downstream configuration. Periphyton established naturally in the mesocosm set-up growing on tile substrates placed to mimic natural streambeds. To simulate point-source loading in the wastewater loading phase, treated sewage effluent from an adjacent treatment plant was pumped directly and continuously into select mesocosms. Inflow and overflow surface water grabs were paired with the collection of periphyton samples on a weekly basis. Samples were analyzed with five qPCR assays detecting FIB including E. coli, enterococci, and Bacteroidales, as well as human host-associated genetic markers (HF183 and HumM2). In surface water samples, culture-based methods were used to measure E. coli and enterococci concentrations. For periphyton, FIB genetic markers were detected in 80-92% of samples, while human-associated markers were detected in less than 5%. In surface water samples, FIB genetic markers were detected in 38-80% of samples and human-associated markers were detected in 5-10%. Results of this study suggest that FIB including host-associated genetic markers can be sequestered by periphyton biofilms.
