Bacterial growth, communication and guided chemotaxis in 3D bioprinted hydrogel environments

Bioprinting of engineered bacteria is of great interest for applications of synthetic biology in the context of living biomaterials, but so far only few viable approaches are available for the printing of gels hosting live Escherichia coli bacteria. Here we develop a gentle bioprinting method based on an alginate/agarose bioink that enables precise printing of E.coli into three-dimensional hydrogel structures up to 10 mm in height. Addition of a calcium peroxide-based oxygen generation system enables maturation of fluorescent proteins deep within the printed structures. We utilize spatial patterning with the bioprinter to control different types of chemical interaction between bacteria. We first show quorum sensing-based chemical communication between engineered sender and receiver bacteria placed at different positions inside the bioprint, and then demonstrate the fabrication of barrier structures defined by non-motile bacteria that can guide the movement of chemotactic bacteria inside a gel.