The Erlanger flagellate test (EFT): photosynthetic flagellates in biological dosimeters

Abstract

The Erlanger flagellate test (EFT) is based on the green unicellular flagellate Euglena gracilis. The organisms are cultivated in minimal medium and used in their stationary growth phase. In order to quantify the effects of toxic substances or solar UV radiation, several physiological parameters are assayed, including motility (percentage of motile cells), swimming velocity, precision of gravitaxis and cell shape. These parameters are highly sensitive to external factors, making this organism an ideal bioassay for a number of toxic substances and UV radiation. The test has been automated using real time image analysis, and the responses have been calibrated. In order to determine the effects of solar UV radiation, the organisms are exposed under different cut-off filters for predetermined periods of time to solar radiation at locations at which physical measurements of radiation are performed simultaneously. The bioassay has been tested extensively for the monitoring of both artificial UV and solar radiation (Greece, Sardinia, Spain, Italy, Sweden, Germany) and for the determination of the toxic effects of heavy metal ions (cadmium, lead, mercury, etc.) and other organic pollutants.