Molecular Approaches in Fecal Source Tracking: The Good, the Bad, and the Ugly.

A number of Fecal Source Tracking (FST) tools are currently used to identify the primary sources of fecal pollution impacting natural water systems. FST is based on the assumption that, given the appropriate method and indicator, the source of microbial pollution can be identified. Most source trackers use molecular methods such as PCR and qPCR assays as they are rapid, sensitive, aimed at well defined targets, are amenable to automated analysis, and can identify multiple sources within a given sample. In this seminar we will examine some of the key elements needed for the successful application of molecular FST methods. Specifically, we will provide results obtained in our laboratory from studies addressing host-specificity, host distribution, and relative abundance of different FST assays against targeted and non-targeted hosts. Examples of successful and not so successful applications will be shared. We will also discuss the need for developing comprehensive molecular databases and the importance of using a systems approach and omics technologies to further develop and validate molecular assays and to better understand the fate and transport of targeted markers.