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DNA detects sources of water contamination

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Photo. Ragnar Våga Pedersen

Feces that end up in water sources can be a health hazard. NIBIO researchers have developed a method that reveals from the source of contamination, i.e. whether the fecal matter is human or stems from various types of animals.

One of the most common reasons we fall ill is that human or animal feces are released into the water we drink or swim in. This is known as fecal contamination.

NIBIO has developed a DNA-based method that can identify the source of contamination. The method primarily consists of three steps, the first being the detection of E. coli and coliform bacteria in water. Intestinal bacteria E. coli is a reliable indicator to signify that the water has been contaminated by feces.

In the next step, DNA tests are used to identify genetic markers specific to a particular host, making it possible to differentiate between different animal groups. In the final step, a so-called contribution profile is developed, indicating which animals the contamination in a water source derives from and to what extent they contribute respectively.

“Using this advanced method enables us to find out whether the source of contamination is human, ruminant, horse, pig or a group we describe as ‘other animal species,’ such as birds or other warm-blooded animals,” explains NIBIO researcher Adam Paruch. He has developed the method together with colleague Lisa Paruch, a molecular biologist at NIBIO.

“Fecal contamination in water can spread microorganisms that pose a health risk. To decide what kind of measures should be taken, it is important to find out where the contamination comes from and what the dominant source is,” he continues.

“By detecting and quantifying the host-specific genetic markers from humans, cows or horses, we can point out exactly where the contamination comes from and implement the remediations accordingly,” Lisa Paruch adds.