3D Printing for the Fabrication of Biofilm-Based Functional Living Materials.

Bacterial biofilms are three-dimensional networks of cells entangled in a self-generated extracellular polymeric matrix composed of proteins, lipids, polysaccharides, and nucleic acids. Biofilms can establish themselves on virtually any accessible surface and lead to varying impacts ranging from infectious diseases to degradation of toxic chemicals. Biofilms exhibit high mechanical stiffness and are inherently tolerant to adverse conditions including the presence of antibiotics, pollutants, detergents, high temperature, changes in pH, etc. These features make biofilms resilient, which is beneficial for applications in dynamic environments such as bioleaching, bioremediation, materials production, and wastewater purification. We have recently described an easy and cost-effective method for 3D printing of bacteria and have extended this technology for 3D printing of genetically engineered Escherichia coli biofilms. Our 3D printing platform exploits simple alginate chemistry for printing of a bacteria-alginate bioink mixture onto calcium-containing agar surfaces, resulting in the formation of bacteria-encapsulating hydrogels with varying geometries. Bacteria in these hydrogels remain intact, spatially patterned, and viable for several days. Printing of engineered bacteria to produce inducible biofilms leads to formation of multilayered three-dimensional structures that can tolerate harsh chemical treatments. Synthetic biology and material science approaches provide the opportunity to append a wide range of useful functionalities to these 3D-printed biofilms. In this article, we describe the wide range of future applications possible for applying functional 3D-printed biofilms to the construction of living biofilm-derived materials in a large-scale and environmentally stable manner.