Extracellular Bacterial Production of DNA Hydrogels–Toward Engineered Living Materials

Engineered Living Materials (ELMs) combine synthetic biology with artificial materials to create biohybrid living systems capable of replicating, self-repairing, and responding to external stimuli. Due to their self-optimization abilities, these systems hold great potential for biotechnological applications. This study is a first step toward ELMs based on DNA hydrogels, focusing on the production of biohybrid materials using the exoelectrogenic bacterium Shewanella oneidensis. To equip the bacterium with the functionality needed for building DNA hydrogels, inducible cell surface anchors are developed, which can bind exogenous polymerase via the SpyCatcher/SpyTag (SC/ST) technology. The process parameters for in situ production of DNA hydrogels are established, enabling the development of these materials in the context of living bacteria for the first time. Using an extracellular nuclease-deficient S. oneidensis strain, stable biohybrid biofilms are generated directly on the surface of bioelectrochemical systems, showing the current generation. Given the high programmability and functionalization potential of DNA hydrogels, it is believed that this study represents a significant step toward establishing dynamic biohybrid material systems that exhibit both conductivity and metabolic activity.