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Team:ETH Zurich/Project
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Overall project
Idea
Our project focuses on the detection of cigarette smoke from the air by e.coli bacteria and monitoring its concentration visually by display of various lights. Our system will act as a smoke sensor and “partymeter”, telling us how a certain party progresses (under the creative assumption that the progress of the party is measured by the amount of smoke in the air).
Project description
We engineer our cells such that they can detect acetaldehyde, which is a substance found in cigarette smoke. Upon binding of acetaldehyde to AlcR, AlcR acts as an inhibitor of gene transcription. This is where our genetically engineered circuit starts. With a number of inhibitors and activators, our circuit gives rise to a GFP output upon sensing acetaldehyde in a certain range of concentration. Our circuit then acts as an acetaldehyde band-pass filter.
Our genetically engineered cells are cultivated in a microfluidic channel and are constantly supplied with a flow of growth medium containing acetaldehyde. They are designed to degrade acetaldehyde, such that a concentration gradient is created along the flow direction within the channel.
Since our cells detect only a certain concentration range of acetaldehyde, as the gradient moves through the channel with varying initial concentration, the GFP stripe that certain cells produce will also "move along". Furthermore, our system acts as a low-pass filter which produces AHL molecules once the acetaldehyde concentration is below a certain threshold (the lower threshold for the previously described band-pass filter). Thus, cells that are behind the GFP stripe will produce AHL. As the stripe moves through the channel, AHL will be always produced to its right and will diffuse in the channel. Moreover, we feed back some of the produced AHL to the channel again, by a "recycling channel", so that even the cells to the left of the stripe are supplied with AHL. As soon as the stripe moves until the end of the channel, no more cells will produce AHL and the recycling will cease after a while. The absence of AHL will trigger RFP production by all the cells. So, in our channel we should be able to see a moving green stripe and a red flash everywhere once the stripe moves to the end of it.
