Background
Bacterial biofilms—three-dimensional networks of cells entangled in an extracellular polymeric matrix composed of organic macromolecules—are platforms for sustainable nano- or biomaterials production and processing. These films can establish themselves on virtually any accessible surface, are resilient to extreme conditions, exhibit high mechanical stiffness, and demonstrate self-assembly and spatial patterning. These features explain why biofilms have recently become hotspots in emerging materials fabrication and additive manufacturing technologies. Genetically tractable bacteria such as Escherichia coli and Bacillus subtilis have been successfully employed for the creation of synthetic biofilms, during the creation of which the following factors must be evaluated: determination of optimal peptide fusion sites, the tolerance of the fusion protein to mutations, the toxicity of the new peptide tags to the bacterial cells, and appropriate functional assays for characterization of the novel biofilm functionalities. Fabrication of biofilm-derived functional materials has been further developed with the aid of 3D printing, for which operating cost has previously been a major challenge.
Technology Overview
Researchers have developed an easy and cost-effective method for 3D printing of bacteria and have extended this technology for 3D printing of genetically engineered E. coli biofilms. The spatial resolution of the 3D-printed biofilms is determined by multiple factors including the bioink composition, the concentration of chemicals that induce expression of the modified biofilm proteins, the rheological properties of the bioink, the biocompatibility of the ink with the printed bacteria, and the surface smoothness of the printing substrate. This platform exploits simple alginate chemistry for printing of biologically and physically robust bacteria-alginate bioink mixture onto calcium-containing agar surfaces, resulting in the formation of bacteria-encapsulating hydrogels with varying geometries.
Benefits
This simple, scalable, and inexpensive approach was used to print biofilms with sub-millimeter precision that can mimic the spatial heterogeneity of natural biofilms. Bacteria in these hydrogels are resistant to antibacterial treatment and remain intact, spatially patterned, and viable for several days and can be used (or engineered) to produce desired chemicals or materials after printing for many environmentally stable functionalities.
Applications
- Biopolymer (i.e. cellulose, curdlan, etc.) production
- enzymatic degradation
- multifunctional sensors
- materials processing
- chemical catalysis
- anti-fouling coatings
- biomedical implants
- environmental detoxification
- wastewater treatment plants
- water purification
- logic gates
- drug development
- pathogen colonization prevention
- environmental sensing and response.