Biofilms are communities of bacteria embedded in a slimy yet extremely tough matrix of extracellular material composed of sugars, proteins and genetic material. During the process of biofilm formation, individual bacteria produce proteins that have the ability to self-assemble outside the cell, creating tangled networks of fibers that keep the cells glued together.
Right from the slippery stones in a riverbed to the plaque on your teeth to the film that develops on the membranes of filters and in pipes, biofilms are commonly found in natural, industrial and hospital settings. While there are many examples of “bad” biofilms and most biofilm related research today focuses on how to get rid of them, a team at the Wyss Institute for Biologically Inspired Engineering at Harvard University has explored the possibility of using biofilms as a robust new platform for designing nanomaterials that could manufacture pharmaceutical products, clean up polluted rivers, and fabricate new textiles.
The team has developed an innovative protein engineering system called BIND (Biofilm-Integrated Nanofiber Display), which in the future could be used for the large-scale production of biomaterials having functionalities that are not possible with existing materials. This proof-of-concept was reported in Nature Communications.
The team fused a protein capable of adhering to steel onto a small protein called CsgA that is produced by the bacterium, E. coli. CsgA gets secreted outside the cell, where it self-assembles into super-resilient proteins called amyloid nanofibers that are stronger than steel and stiffer than silk. It was observed that these amyloid proteins retained the functionality of the added protein, ensuring that the biofilm adhered to steel. Amyloid proteins are infamous for being the causative agents of some diseases such as Alzheimer’s, but in this case their role is fundamental to making BIND very robust. The team was able to fuse 12 different proteins to the CsgA protein, with varying sequences and lengths. In principle, this means that they can use this versatile technology to manufacture or immobilize virtually any protein with a specific functionality in large quantities.
This is one of the first studies that aims to bridge the gap between synthetic biology and biomaterials research. It offers a glimpse into a much more environmentally sustainable future where large factories are reduced to the size of a cell that can be programmed to produce new materials that meet our everyday needs, from textiles to energy and environmental cleanup.
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