Comparison of amplicon sequencing to conventional fecal source tracking techniques in the Navesink River

Fecal indicator bacteria are commonly used to evaluate water quality and make decisions on designating and restricting use. A drawback of this method is it does not differentiate fecal sources for management purposes. Microbial source tracking is being explored as an alternative and more informative method of assessing and identifying contaminant sources. High throughput sequencing of the 16s rRNA region allows for rapid, large scale microbial community analyses and is an attractive source tracking method that has not been thoroughly explored. To investigate the effectiveness of this method, samples were collected from representative fecal sources from horse, dogs, geese, and wastewater then mixed in known quantities to create a fecal library. A series of field samples were collected during wet and dry weather from the Navesink River, Red Bank, New Jersey. The library and field samples were evaluated for fecal coliform, qPCR for fecal marker genes, and those results were compared with the microbial community fingerprints generated by amplicon sequencing. The results from all three techniques were cross compared to understand the consistency of results between methods, and will inform the application of amplicon sequencing for source tracking in surface waters impacted by fecal/bacterial contamination. Results showed significant differences in library samples with biomarkers that could be applied with success to select sites with elevated coliform results; indicate further biomarker investigation is needed in sequencing results.M.S.Includes bibliographical referencesby Sarah Phela