Towards light-mediated sensing of bacterial comfort

Bacterial comfort is central to biotechnological applications. Here, we report the characterization of different sensoring systems, the first step within a broader synthetic biology-inspired light-mediated strategy to determine Escherichia coli perception of environmental factors critical to bacterial performance. We did so by directly 'asking' bacterial cultures with light-encoded questions corresponding to the excitation wavelength of fluorescent proteins placed under the control of environment-sensitive promoters. We built four genetic constructions with fluorescent proteins responding to glucose, temperature, oxygen and nitrogen; and a fifth construction allowing UV-induced expression of heterologous genes. Our engineered strains proved able to give feedback in response to key environmental factors and to express heterologous proteins upon light induction. This light-based dialoguing strategy reported here is the first effort towards developing a human-bacteria interphase with both fundamental and applied implications.

The results we present here are at the core of a larger synthetic biology research effort aiming at establishing a dialogue with bacteria. The framework is to convert the human voice into electric pulses, these into light pulses exciting bacterial fluorescent proteins, and convert light-emission back into electric pulses, which will be finally transformed into synthetic voice messages. We report here the first results of the project, in the form of light-based determination of key parameters for bacterial comfort. The ultimate goal of this strategy is to combine different engineered populations to have a combined feedback from the pool.