Mechanically Tunable, Compostable, Healable and Scalable Engineered Living Materials

Novel design strategies are essential to realize the full potential of Engineered Living Materials (ELMs), including their biodegradability, manufacturability, sustainability, and ability to tailor functional properties. Toward these goals, we present Mechanically Engineered Living Material with Compostability, Healability, and Scalability (MECHS), a material that integrates these features in the form of a stretchable plastic that is simultaneously flushable, compostable, and exhibits the characteristics of paper. This plastic/paper-like material is produced directly from cultured bacterial biomass (40%) producing engineered curli protein nanofibers in scalable quantities (0.5-1 g L-1). The elongation at break (1-160%) and Youngs modulus (6-450 MPa) of MECHS was tuned to more than two orders of magnitude. By genetically encoded covalent crosslinking of curli nanofibers, we increase the Youngs modulus by two times. MECHS biodegrades completely in 15-75 days, while its mechanical properties are comparable to petrochemical plastics and thus may find use as compostable materials for primary packaging.