We want to produce new natural products in bacteria. To reach this goal, we need to be able to detect trace amounts of these substances. We will demonstrate how this works by detecting traces of cocaine on your banknotes. Such traces can be detected on almost all banknotes since the threshold for the detection of cocaine is incredibly low. You could dissolve a pinch of cocaine in a swimming pool. After dispersing it, a small drop of the water would be enough to detect it. The mass spectrometry method we use here is used in forensics by the police to detect drugs, but also to detect pesticides in ground water or food. Our group is using this highly sensitive analytical method to find new microbes that produce natural products. To identify novel substances, we modify the genetics of known bacterial producers of natural products. Since the production of such unnatural substances initially is very limited, we need highly sensitive detection methods. As soon as we can detect small traces of the new natural products we search for the best producing organisms and try to optimize the production further. We are hoping to "breed" tailor-made antibiotics in this way.