DNA detection applied increasingly widely
KWR develops DNA methods that permit one to trace the sources of faecal contamination in water. In 2012 and 2013, in a commission from the Dutch Directorate for Public Works and Water Management (Rijkswaterstaat), researchers analyse water samples taken at 19 bathing locations to establish what animals are the source of possibly present faecal bacteria. In 2013, for the first time, dogs were studied as a possible source. Water managers can use this information to take targeted measures.
The Netherlands has about 670 natural bathing locations. These have to meet the standards established in the Bathing Water Guideline (EU 2006). High concentrations of faecal bacteria – indicative for the possible presence of pathogens – can constitute grounds for closing a location. The sources of faecal bacteria are, for example, recreationists, birds, cows and dogs. Using quantitative PCR methods (qPCR), in which a specific DNA fragment (marker) is amplified, one can quickly determine what sources of faecal contamination are involved.
Clarity for water managers
The sample analyses indicate that bathing water contains bird faeces at the majority of the investigated locations. At a number of locations, human faecal bacteria were detected – often due to recreation, recreational or professional boating, sewage overflow or the presence of a wastewater treatment plant close to the bathing location. At several locations the bathing water contains faecal bacteria from cows and dogs. The highest concentration of dog-specific markers was detected at “dog beaches”. In 2014, the researchers would like to include horses in the research as well.
Wide application in the water cycle
Apart from source-tracing in bathing water, DNA techniques are applied for the tracing sources of contamination in the drinking water cycle. Within the water sector’s joint research programme (BTO), DNA techniques are being applied to trace sources in samples taken from water abstraction sites and water mains, so as to extend our knowledge about the potential presence and sources of micro-organisms.
© 2018 KWR Watercycle Research Institute
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Manager Microbial Water Quality and Health and scientific researcher