Applicability of a yeast oestrogen screen for the detection of oestrogen-like activities in environmental samples

A (xeno)oestrogen bioassay was introduced, using a genetically modified yeast strain which produces a fusion protein encompassing the human oestrogen receptor hormone binding domain and the yeast GAL4-DNA binding domain. Upon binding of appropriate substances this fusion protein recognises the respective DNA sequence thereby enhancing the transcription of a β-galactosidase reporter gene. The bioassay procedure was evaluated by screening 30 compounds, including some known or suspected (xeno)oestrogens and determining EC50-values for 17β-oestradiol, 1.5 nM, 4-tert.-octylphenol, 6.7 μM and bisphenol A, 104 μM. Toluene extracts from different environmental matrices were tested for their oestragenic activity. The positive test results obtained with a sewage sludge extract indicated the applicability of this bioassay for environmental monitoring.