Successful application of umu test in KWR laboratories

Effect-based water-quality measurements

The number of different chemicals encountered in water is increasing worldwide. This reflects the fact that more and more chemicals are coming onto the market, but also that measurement methods are becoming increasingly refined. The compounds are simply being better picked up by sensitive equipment. Measuring concentrations of all compounds in a water sample is difficult and frequently produces insufficient information about toxicity. A key concern in water-quality research are the potential harmful effects of chemicals on biological processes and on DNA.

This is studied by means of effect-based water-quality measurements with bioassays. The Ames fluctuation test is commonly used to study DNA damage. But there are several bioassays available, and KWR’s microbiology laboratory, together with the institute’s researchers, have concluded that the umu test is also particularly suited for this purpose. With the umu test one can both determine the water quality of a drinking water source as well as the effectiveness of a water treatment process. ISO 13829 provides a standard guideline for the application of the umu test for the assessment of water quality.

How the umu test works

The umu test uses special bacteria and is based on the activation of the so-called ‘umuC gene’. This gene is expressed as soon as the DNA in the bacteria is damaged. When the DNA damage occurs, the bacteria releases enzymes which in the test cause a colourless substrate to turn yellow. The spectrophotometer measures the degree of colour change, making it possible to quantify the damage to the genetic material.

When applied to a water sample, the test clearly indicates the extent of the presence of harmful compounds. Based on the results, KWR is researching more closely the possibility of using the umu test and other bioassays to assess the health risks presented by compounds in water. ‘With our microbiology laboratory’s research, we want to help drinking water utilities get a reliable, rapid and cost-efficient picture of water quality,’ says KWR researcher Astrid Reus.

Total package of water-quality research

The bioassays are conducted in a close collaboration between KWR’s microbiology and chemical laboratories. Water samples are pre-treated in the chemical laboratory and then tested in bioassays in the microbiology laboratory. A combination with chemical methods can make it possible to show which compounds cause an effect in a bioassay. In the chemical laboratory, we also research which water contaminants are present and what the consequences are for water quality.

The methods used include non-target screening by means of high-resolution mass spectrometry. With its advanced equipment and technologies, KWR provides a total package of water-quality research. We are leaders in the application of existing, and the development of innovative, analytical methods in the interest of water quality, today and into the future.