Karlsruhe Institute of Technology

Given that the ultimate goal of ecotoxicology is the identification of effects at the population and ecosystem levels, microbial communities were picked for reasons of their supreme importance in the environment. Two microbial communities (intestinal microbiomes and environmental microbial biofilms) will be investigated with respect to effects by the test substances (cf. WPs 1 and 2). The intestinal biofilm population shifts may be responsible for the health status of the aquatic organisms, whereas
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WP 2 will address metabolites and transformation products (TPs) of compounds selected in WP 1. These will be generated and identified by means of electrochemical synthesis mimicking mainly Phase I metabolism and mass spectrometric detection. The mixture of metabolites and TPs will be used for ligand screening with nuclear receptors (WP 3) using the analytical methodology devel-oped as well as for further toxicity screening for effects on cells (WP 4) and in biota (WPs 5 and 6).

Results of the multi-level scale approach on effects for the selected micropollutants and their TPs and metabolites will be evaluated and integrated as a base for the creation of a tool box for the ef-fect-based risk assessment. Results will stimulate further work in the development of models linking exposure and effect data with hydrological models. This will require the correlation of results from receptor assays, cell lines and animal models. Microbial data will be linked to the health status
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This WP will provide data for receptor binding of the tested xenobiotics at a molecular level in cell-free systems, since in most cases the binding of a compound to a receptor molecule implicates a biological effect, either agonistic or antagonistic. However, since biological approaches are not ca-pable of identifying the chemical structures of environmental contaminants, feasible combinations of bioassays and chemical analysis will be developed and tested. As a pretreatment step concepts of an
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WP 1 first aims at identifying and quantifying relevant test substances from the groups of pharma-ceuticals (antidiabetics and neuroactive drugs such as selective serotonin reuptake inhibitors) and food additives (artificial sweeteners) in surface waters partly using existing expertise. The focus is on substances of high consumption and environmental relevance. Based on this analysis, the final test compounds will be defined (e.g. metformin, fluoxetine and sucralose), and specific methods for
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