Abstract

We create a bacterio-quantifier of smoke. SmoColi cells are engineered to sense toxic substances found in cigarette smoke (for example acetaldehyde or xylene). They are immobilized in a microfluidic channel, in which a concentration gradient of the toxic substance is established. The sensor is linked to a band-pass filter that leads to input-concentration-dependent GFP expression. Continuous increase of the input concentration and its detection, therefore, establishes a moving fluorescent band in the channel. Finally, if the input concentration exceeds a certain threshold, cells produce RFP and the device turns red. Due to its modularity, our SmoColi system can be used in fact as a quantifier for a range of substances, as long as the sensor is adapted. To show that our system can be activated by different signals, as a proof of principle, we modified the circuit so that it can be induced by arabinose.