Interaction of different yeast species allows bio-economic detection of pharmaceutical residues

The active ingredient diclofenac is one of the most widely used anti-inflammatory pharamaceuticals in the world. When consumed orally, 60-70% of the active ingredient is excreted in the urine. Diclofenac thus enters wastewater and, even at low concentrations, can have a negative impact on the environment, for example causing damage to the gills and kidneys of fish.

In the cooperative project ISAr the scientists of the Biological Sensor-Actor Systems group of TU Dresden work together with the Kurt Schwabe Institut für Mess- und Sensortechnik Meinsberg e.V. (KSI Meinsberg e.V.) in order to develop a sustainable and low budget yeast cell-based sensor for the detection of diclofenac in environmentally relevant concentrations in soil and wastewater.

The detector is based on immobilized yeast cells in a suitable technical readout device and is intended to be used as a rapid, on-site alternative to the existing rather expensive laboratory diagnostic methods.

The system is based on yeast cells (Saccharomyces cerevisiae, S.c.) that form a fluorescent protein in the presence of diclofenac. For reliable technical readout, however, the corresponding fluorescence signal must be amplified. For this purpose, the TU Dresden team led by Dr. Kai Ostermann is working on the implementation of an innovative, intrinsic, cell-based amplification system to achieve a significant amplification of the fluorescence signal.

"With the measurement setup developed in the previous BioSAM project, we can detect diclofenac in a range of 5 - 50 μM. However, the sensitivity of this system is still too low to detect the relevant concentrations of diclofenac in wastewater or soil water. Therefore, we aim to increase the sensitivity of diclofenac detection using reporter yeasts to lower the concentration range. To this end, we will first conduct extensive studies on the modulation of cell-cell communication and signal amplification using the yeast pheromone-based system of controlled cell-cell communication that we have developed and patented for the first time. If a reporter yeast reliably communicates that it has detected diclofenac to many other yeast cells and the other yeast cells are thereby stimulated to fluoresce, we can achieve stable signal amplification," Ostermann explains.

Prof. Michael Mertig and his team at KSI Meinsberg will subsequently implement the results achieved in this first process in a real demonstrator setup suitable for on-site measurements using sensor technology. "By increasing the detection sensitivity, such a detector could be used advantageously in various places, including monitoring wastewater from hospitals and retirement homes, the pharmaceutical industry, and in regional wastewater treatment plants," says Prof. Mertig, describing the goal of the project.

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