A de novo matrix for macroscopic living materials from bacteria

Engineered living materials (ELMs) embed living cells in a biopolymer matrix to create novel materials with tailored functions. While bottom-up assembly of macroscopic ELMs with a de novo matrix would offer the greatest control over material properties, we lack the ability to genetically encode a protein matrix that leads to collective self-organization. Here we report growth of ELMs from Caulobacter crescentus cells that display and secrete a self-interacting protein. This protein formed a de novo matrix and assembled cells into centimeter-scale ELMs. Discovery of design and assembly principles allowed us to tune the mechanical, catalytic, and morphological properties of these ELMs. This work provides novel tools, design and assembly rules, and a platform for growing ELMs with control over matrix and cellular structure and function. One-Sentence SummaryWe discovered rules to grow bacteria into macroscopic living materials with customizable composition, structure, and function.