A biological filter to remove estrogens from waste water and drinking water. The 15 Bielefeld students submitting this project to the 'international Genetically Engineered Machine competition' (iGEM) at the Massachusetts Institute of Technology (MIT) in Boston, USA are setting their sights high. They are persuading internationally active companies and associations in the biotechnology and chemistry sector to contribute several ten thousands of Euros to cover the costs of entering this rapidly expanding global competition in synthetic biology. Since May, they have been spending their free time in the laboratory making new DNA building blocks, reproducing them, and producing enzymes. First results give reason for optimism.