Engineered Bacillus subtilis biofilms as living glues

The powerful biological adhesion systems of barnacles, mussels, and other marine animals have led to bio-inspired adhesives with impressive performance characteristics. However, lacking the capacities that only cells possess (e.g., self-regeneration, environmental responsiveness, etc.), these artificial materials cannot exploit the full potential of the natural adhesive systems that inspired them. Here, we developed “functional cellular glues” made of Bacillus subtilis biofilms—tightly associated bacteria encased in an extracellular matrix—that contain both an engineered amyloid protein functionalized with a mussel foot protein and an engineered hydrophobin-like protein. We demonstrate proof-of-concept for both tunable adhesion performance via inducible enzymatic modification and for improved adhesion through metal ion-assisted curing. By conceptualizing biofilms themselves—rather than individual material components—as adhesives, we have developed an evolvable engineering platform that opens the door to make smart living glues with dynamic, self-healing, and other previously unattainable material properties.