Ultra-lightweight living structural material for enhanced stiffness and environmental sensing

Natural materials such as bone, wood, and bamboo can inspire the fabrication of stiff, lightweight structural materials. Biofilms are one of the most dominant forms of life in nature. However, little is known about their physical properties as a structural material. Here we report an Escherichia coli biofilm having a Young's modulus close to 10 GPa with ultra-low density, indicating a high-performance structural material. The mechanical and structural characterization of the biofilm and its components illuminates its adaptable bottom-up design, con-sisting of lightweight microscale cells covered by a dense network of amyloid nanofibrils on the surface. We engineered E. coli such that 1) carbon nanotubes assembled on the biofilm, enhancing its stiffness to over 30 GPa, or that 2) the biofilm sensitively detected heavy metal as an example of an environmental toxin. These demon-strations offer new opportunities for developing responsive living structural materials to serve many real-world applications.

Automated summary

Natural materials like bone, wood, and bamboo can inspire the creation of stiff and lightweight structural materials. Biofilms, one of nature's most dominant life forms, have been found to possess physical properties suitable for structural materials. In this study, an Escherichia coli biofilm with a Young's modulus close to 10 GPa and ultra-low density was discovered, suggesting its potential as a high-performance structural material. By engineering E. coli, carbon nanotubes were incorporated into the biofilm, increasing its stiffness to over 30 GPa, and the biofilm was also able to detect heavy metals as environmental toxins. These findings open up new possibilities for developing responsive living structural materials for various real-world applications.