Biocircuit design through engineering bacterial logic gates

Designing synthetic biocircuits to perform desired purposes is a scientific field that has exponentially grown over the past decade. The advances in genome sequencing, bacteria gene regulatory networks, as well as the further knowledge of intraspecies bacterial communication through quorum sensing signals are the starting point for this work. Although biocircuits are mostly developed in a single cell, here we propose a model in which every bacterium is considered to be a single logic gate and chemical cell-to-cell connections are engineered to control circuit function. Having one genetically modified bacterial strain per logic process would allow us to develop circuits with different behaviors by mixing the populations instead of re-programming the whole genetic network within a single strain. Two principal advantages of this procedure are highlighted. First, the fully connected circuits obtained where every cellgate is able to communicate with all the rest. Second, the resistance to the noise produced by inappropriate gene expression. This last goal is achieved by modeling thresholds for input signals. Thus, if the concentration of input does not exceed the threshold, it is ignored by the logic function of the gate.