Genetically engineered bacteria make living materials for self-repairing walls and cleaning up pollution

With just an incubator and some broth, researchers can grow reusable filters made of bacteria to clean up polluted water, detect chemicals in the environment and protect surfaces from rust and mold.

I am a synthetic biologist who studies engineered living materials – substances made from living cells that have a variety of functions. In my recently published research, I programmed bacteria to form living materials that can not only be modified for different applications, but are also quick and easy to produce.

From living cells to usable materials

Like human cells, bacteria contain DNA that provides the instructions to build proteins. Bacterial DNA can be modified to instruct the cell to build new proteins, including ones that don’t exist in nature. Researchers can even control exactly where these proteins will be located within the cell.

Because engineered living materials are made of living cells, they can be genetically engineered to perform a broad variety of functions, almost like programming a cellphone with different apps. For example, researchers can turn bacteria into sensors for environmental pollutants by modifying them to change color in the presence of certain molecules. Researchers have also used bacteria to create limestone particles, the chemical used to make Styrofoam and living photovoltaics, among others.

Living organisms can be used to “grow” materials to make clothes and furniture.

A primary challenge for engineered living materials has been figuring out how to induce them to produce a matrix, or substances surrounding the cell, that allows researchers to control the physical properties of the final material, such as its viscosity, elasticity and stiffness. To address this, my team and I created a system to encode this matrix in the bacteria’s DNA.

We modified the DNA of the bacteria Caulobacter crescentus so that the bacterial cells would produce on their surfaces a matrix made of large amounts of elastic proteins. These elastic proteins have the ability to bind to each other and form hydrogels, a type of material that can retain large amounts of water.

When two genetically modified bacterial cells come in close proximity, these proteins come together and keep the cells attached to each other. By surrounding each cell with this sticky, elastic material, bacterial cells will cluster together to form a living slime.

Furthermore, we can modify the elastic proteins to change the properties of the final material. For example, we could turn bacteria into hard construction materials that have the ability to self-repair in the event of damage. Alternatively, we could turn bacteria into soft materials that could be used as fillers in products.

The living material advantage

Usually, creating multifunctional materials is extremely difficult, due in part to very expensive processing costs. Like a tree growing from a seed, living…

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