The technology enables researchers to identify the culprit of contamination, much as human DNA analysis or fingerprinting is used by law enforcement. Bacterial DNA is isolated and digested with a restriction enzyme that cleaves the nucleic acid at a specific sequence. The resulting DNA fragments are separated by electrophoresis in an agarose gel, transferred to a nylon membrane, and hybridized with a labeled probe. The label enables the DNA banding pattern to be visualized, and sizes are assigned to each band according to a molecular weight marker. The analysis process is facilitated by a database administered at the University of Florida.
Coliphages are viral indicators of enteric pathogens in environmental samples.
Groups I and IV are generally indicative of animal feces whereas groups II and III are more human-specific. This technology has only been applied in a few locations worldwide, so hundreds of South Carolina isolates will be compared to reference samples to check for variations in coliphage distributions. The current surface water project is expected to be completed in the spring of 2001. Preliminary analyses suggest that MAR, ribotyping and coliphage typing differ in their sensitivity and ability to track fecal pollution sources. It is likely that a combination of source tracking procedures will emerge as the best approach to addressing watershed clean-up efforts.