Synthetic photobiology for light controllable active matter

ongoing

From a Physics and Engineering standpoint, swimming bacteria are a formidable example of self-propelled micro-machines. Together with their synthetic counterpart, self-propelled colloids, they represent the “living” atoms of active matter, an exciting branch of contemporary soft matter and statistical mechanics. Differently from synthetic colloids, however, each bacterial cell contains all the molecular machinery that is required to self-replicate, sense the environment, process information and compute responses. Breaking down these biological functions into basic genetic parts has been one of the greatest triumphs of molecular biology. Today, synthetic biologists are assembling these parts into new genetic programs and exploiting bacteria as computing micro-machines. Project SYGMA will employ the synthetic biology toolkit to provide the building blocks for a light controllable active matter having reliable, reconfigurable and interactively tunable dynamical properties. We will first engineer transmembrane photoreceptors to wire RGB external light signals to cellular physical responses like speed, tumbling, growth and death rates. These genetic parts will allow the modular design of customized active particles to build active materials with unprecedented optical control capabilities. Using these new tools we will address, with experiments and theory, fundamental questions like: how fast can we drive particle density using spatio-temporal motility modulations? what is the force on a body suspended in a bath of bacteria with non uniform motility? how do physical forces contribute to morphogenesis in bacterial colonies? Finding quantitative and experimentally validated answers will eventually allow us to engineer structured illumination protocols to mold living microstructures, transport colloidal cargos by shaping active pressure, control swarms of biohybrid microcars and shape bacterial microcolonies.