Innovating with bacteria

 Bio-films of microbial material are, to understand us, like those that cause dental plaque. Others cause more serious problems and generally, being made up of bacteria, do not get a good press. However, a group of researchers at Harvard University's Wyss Institute for Biologically Inspired Engineering sees these bacterial films as a solid platform to support designer nanomaterials, which could serve to clean polluted rivers or make new pharmaceuticals or fabrics.

To do this, they have developed a protein engineering system called BIND (Biofilm Inspirated Nanofiber Display), something that tomorrow could facilitate the large-scale production of biomaterials, which could be programmed to perform functions that currently, with the existing materials, it is not possible. These first attempts appeared this week in the journal Nature Communications.

"Most biofilm research today is focused on how to dispose of these films, but here we show that we can engineer these materials to perform specific functions, in specific amounts and for specific applications," explained Dr. Neel. Joshi, a member of the Wyss Institute and lead author of the study.

These biofilms are also capable of self-assembling and self-repairing. "If they are damaged, they grow back because they are living tissues," said Peter Nguyen, a researcher also participating in the study.

Self-assembly and self-repair

Biofilms are communities of bacteria embedded in a soft but extremely resistant matrix of extracellular material, composed of sugars, proteins and genetic material. Joshi's team succeeded in altering the composition of the extracellular material, turning it into a self-replicating production platform, ideal for whatever material they wish to produce.

For example, the team genetically fused a protein with a particular function - to adhere to steel - to another small protein called csgA that is produced by the bacterium E. coli. The attached component is then lost in the natural process by which csgA is secreted outside the cell, where it self-assembles into proteins called amyloid nanofibers. These amyloid proteins were, however, capable of conserving the functionality of the added protein, ensuring in this case that the biofilm adheres to the steel.

"We are also very excited about the versatility of the method," said Joshi. The team demonstrated the ability to fuse 12 proteins with different sequences and lengths to the csgA protein. This means, in principle, that they can use this technology to create biofilms with not one, but several functions.

"We are basically programming the cells to be manufacturing plants," Joshi said. For now, the team has demonstrated their ability to program biofilms of E. coli (a recurring intestinal bacterium) to adhere to certain substrates, such as steel, immobilize a set of proteins, or promote the creation of silver templates for construction. of nanowires.