3D Printing Bacteria Biofilms for the Construction of Living Materials

Srikkanth Balasubramanian, Marie-Eve Aubin-Tam, and Anne S. Meyer explore the idea of 3D printing with bacteria further in their recently published ‘3D Printing for the Fabrication of Biofilm-Based Functional Living Materials.’ With a focus on the power bacterial biofilms could have in a variety of applications, the researchers explain the benefits of these CD cell networks made up of proteins, lipids, polysaccharides, and nucleic acids.

As organic platforms for production and processing of biomaterials, the bacterial biofilms not only self-assemble and settle into spatial patterning, but they are also tough, demonstrating high mechanical stiffness, and resistance to high temperatures, antibiotics, pollutants, detergents, and more. The authors expect biofilms to be beneficial for applications like the following:

• Bioleaching
• Bioremediation
• Materials production
• Wastewater purification

Synthetic biology allows researchers to refine and strengthen the performance of ‘biofilm-forming bacteria,’ with the use of additional peptides and ‘genetically tractable bacteria’ like Escherichia coli and Bacillus subtilis in use for synthetic, engineered materials. In creating such biofilms, the following must be assessed:

• Determination of optimal peptide fusion sites
• Tolerance of fusion protein to mutations
• Toxicity of new peptide tags to the bacterial cells
• Functional assays for characterization of novel biofilm functionalities

“The resultant biofilm-derived materials can exhibit marked advantages over materials fabricated by planktonic bacteria cultures, in terms of their resistance to extreme and unexpected environments, reusability, spatial multiscale patterning, and tunable properties,” state the researchers.

Possible applications of 3D-printed synthetic biofilms. Bacteria can be genetically engineered to produce structural biofilm proteins (in blue) decorated with specific functional peptides (in green) via heterologous expression in a bacterial strain that has a genetic deletion for structural biofilm proteins. By combining these engineered bacteria with 3D bioprinting, 3D-printed engineered biofilms can be created with multiple potential applications, including (A) Environmental detoxification and bioremediation, (B) Biomedical applications, (C) Tunable materials production with improved mechanical and/or conductive properties, (D) Fabrication of responsive materials, (E) Biocatalysis-driven materials processing, (F) Addressing fundamental research questions, and (G) Creation of reproducible model biofilm systems for studying the structure–function relationships of bacterial biofilms.

There are challenges and concerns in using genetically modified bacteria, obvious, with the authors stating that 3D printed devices could then potentially be toxic and a hazard to humans—and the environment—should the bacteria be exposed.

“For societal applications such as drinking water plants, contamination risks could be eliminated by 3D printing cell-free functional extracellular matrix components that were isolated from biofilms by vacuum filtration. Such components will have longer stability and reusability compared to living bacteria and would not need constant maintenance,” concluded the researchers.

“Overall, the effectiveness, stability, and versatility of 3D bioprinting approaches in combination with the distinct characteristics of bacterial biofilms offer an ideal platform for the fabrication of biofilm-derived products in materials processing and manufacturing.”

You might be surprised to find out how often 3D printing and research regarding bacteria have been connected, from studies into stem-cell engineering to manufacturing living materials to fabricating cyanobacteria.

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