Assessment of Sources and Diversity of Male-Specific Coliphages for Source Tracking

Abstract

Watershed managers and utilities responsible for source water protection are looking for ways to minimize risk from both human and nonhuman pathogen reservoirs. The ability to accurately identify microbial input source(s) would allow water managers to develop and apply effective, cost-efficient corrective measures. In this study, the potential role of F-specific coliphages with a special focus on the F+DNA coliphages as delineators of sources of surface water microbial pollution was investigated. A variety of source samples from across the United States were analyzed including wastewater and septic system samples, animal slurry lagoon samples, and freshly voided animal fecal samples. Samples were analyzed for fecal coliforms, F-specific coliphages, and somatic coliphages. F-specific phages were isolated and typed to determine whether they were F+RNA or F+DNA coliphages, and were subsequently serotyped and genotyped. F-specific coliphages were detected more often in wastewater samples and slurry lagoon samples when compared to individual fecal samples, where they were rarely detected. F+DNA coliphages were detected in all wastewater samples, in two cow manure samples, and were absent from avian fecal samples. Serotyping and genotyping analysis of F+DNA coliphages did not exclusively associate one subtype with human or animal wastes. A significant proportion of F+DNA isolates demonstrated inconclusive serotyping results, although a majority of the solely M13 serotyped isolates were from domestic wastewater sources. In wastewater samples, 77% were F+DNA while 23% were F+RNA coliphages. Consistent with previous studies, F+RNA coliphage serotyping analysis demonstrated a predominance of group II and III F+RNA coliphages in the wastewater samples, whereas group I and group IV predominated in animal fecal samples and animal slurry lagoon samples. Overall, the results from this study suggests that the presence of F+DNA coliphages, and especially M13 type F+DNA coliphages, could be a potential indicator of human-related wastes.