The aim of project ColiBot was to create a robot-bacteria interface. Information processing is done by a bacterial culture that exhibits a feedback loop with a mobile robot. To enable communication between bacteria and robot, we decided to engineer Escherichia coli cells to respond to environmental changes with an increase in fluorescence in the culture. To achieve environment-dependent expression of fluorescence proteins, we used the temperature-inducible ibpA-promoter and two promoters which respond to shifts in pH, the acid-inducible asr-promoter and the alkaline-inducible alx-promoter.
Video about our project. This video gives a short overview of project ColiBot.
An important area at the cutting edge of technology is the integration of biological systems in mechanical and automated systems. For our iGEM project we therefore chose to take a new approach on the integration of biology into technology. Our goal was the creation of a robot-bacteria interface that acts in a constant feedback loop. The first step was to make communication between bacteria and a technical system possible. Therefore, we engineered E. coli cells, which are sensitive to certain environmental conditions. When these conditions are met, the bacteria will express certain detectable proteins. In our setup a mobile robot moves through an arena and uses its proximity sensors to measure whether there is a wall in front of it. If the robot detects a wall, a signal will be transferred to a bacterial culture in the form of an environmental change. To provide them with stable conditions, the bacteria are cultivated in a bioreactor. In the bacteria, promoters sensitive to the these environmental changes will be activated and promote the expression of a fluorescent protein. The resulting fluorescence signal can be detected by an optical system and relayed back to the robot resulting in a response in form of a directional change. For the realization of this concept we created a temperature-sensitive construct first. The heat shock promoter ibpA controls the expression of one fluorescent protein, which allows a simple yes/no decision. We used it for preliminary experiments to move a robot through a maze. To expand the possibilities of communication we created constructs sensitive to acidic and alkaline pH. The acid-inducible asr-promoter and the alkaline-inducible alx-promoter are used to control the expression of two different fluorescent proteins. A shift in pH-value will lead to a change of fluorescence and allow navigation of the robot in a more sophisticed way.