Bacterial Swarming-Guided Biomineralization Enables Pattern Formation in Engineered Living Materials

Abstract

Engineered living materials (ELMs) harness the adaptive and self-replicating capabilities of biological systems to create functional materials for sensing, catalysis, and biomineralization. While most ELM strategies rely on static microbial assemblies, the role of bacterial motility in structuring living materials remains unexplored. Here, for the first time, we demonstrate how swarming motility in Escherichia coli MG1655 can be induced to guide spatio-temporally organized calcium phosphate mineralization. The mineralized calcium phosphate is characterized by scanning electron microscopy and elemental analysis. By systematically varying phosphate sources and their concentrations in calcium-rich media, we observe the emergence of regularly spaced concentric mineralized patterns. The previously undocumented observation of the concentric patterns was rationalized through a continuum model that captures the spatiotemporal coupling between swarm expansion and mineral deposition. The model shows that this coupling can generate recurrent front arrest and restart, leading to concentric ring formation. Finally, we show that altering the phosphate species results in distinct mineral morphologies. Together, this work establishes a novel framework for integrating bacterial swarming with biomineralization, enabling dynamic and programmable pattern formation in ELMs.