Published by Communications and Public Affairs (519) 824-4120, Ext. 56982 or 53338
August 23, 2004
‘Genetic code library’ provides clues about water contamination
University of Guelph researchers are doing some detective work to identify possible sources of water contamination using unique E. coli bacteria DNA “fingerprints.”
Pathobiology professor Carlton Gyles and researchers Shu Chen and Joseph Odumeru of the University’s Laboratory Services are mapping out E. coli gene patterns in livestock, wildlife and human waste. With this information, the researchers have built a library of identifiable E. coli DNA patterns that can be used to pinpoint the offending species of origin.
Water contamination from faecal waste is difficult to trace, Gyles said. “Identifying the source of E. coli contamination in water samples is a very important first step in controlling water contamination. The longer it takes to identify the contamination source, the longer it takes to manage and control the problem.”
There are thousands – if not millions – of E. coli strains that have adapted to different animals over time, he said. Genes from these bacteria reflect these adaptations and can be detected by analyzing the bacterial DNA.
Gyles and his research group have done just that: they’ve analyzed the DNA from E. coli that originate from livestock, wildlife and humans, and formed a library of DNA patterns. E. coli DNA isolated from contaminated water samples can then be compared with DNA in the library.
Gyles cautioned this approach may only be useful within a local region, since E. coli strains differ from one area to another. The small initial library was used as a model for testing, so the researchers are now expanding the library before using it to test real samples from the environment. If the DNA of an offending E. coli in a water sample can be matched to DNA from the library, then the species of origin would be easily identified.
Testing for the new library began last spring and continues through the summer. “Not only is faecal contamination foul, it poses a human health risk,” said Gyles. “Controlling contamination in a more timely manner will mean shorter closure periods for public beaches and faster remedies for contaminated well water.”
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