Materials

Brightly Colored Bacteria Engineered Into Living Paint

A new, organic technique produces non-toxic, biodegradable paints that shine as brilliantly as peacock feathers and butterfly wings.

The image shows a colony of the Flavobacterium IR1, 2 cm in diameter, growing on a nutrient agar plate. The cells in the colony are highly organized, thus forming a 2-D photonic crystal that interferes with light. This results in structurally colored bright and angle-specific hues with a concentric ring pattern indicating subtle changes in organization. The older cells of IR1 in the colony centre are more disorganized and therefore loses color. IR1 can be genetically modified from this wild-type strain to create new, living photonic structures. | University of Cambridge
The image shows a colony of the Flavobacterium IR1, 2 cm in diameter, growing on a nutrient agar plate. The cells in the colony are highly organized, thus forming a 2-D photonic crystal that interferes with light. This results in structurally colored bright and angle-specific hues with a concentric ring pattern indicating subtle changes in organization. The older cells of IR1 in the colony centre are more disorganized and therefore loses color. IR1 can be genetically modified from this wild-type strain to create new, living photonic structures. | University of Cambridge

Now here's a bright idea.

Researchers in Europe have developed a technique for growing genetically modified bacteria that can be used as brightly colored “living paints” in manufacturing and art.

The colors generated by the bacteria, shiny and metallic, are actually generated by the same optical process that makes peacock feathers and butterfly wings so visually striking. The color comes not from organic pigments, but rather the very molecular structure of the bacterial colony.

In a collaboration between the University of Cambridge and the Dutch company Hoekmine BV, researchers developed the unique process by genetically modifying colonies of flavobacteria, a kind of bacteria that produces colors as a byproduct of its own internal structure. Depending on how the genetics are manipulated, the bacteria reflect light at different wavelengths, potentially including all colors of the visual spectrum.

The new research could provide manufacturers with biodegradable, non-toxic paints that are grown instead of synthesized.

The new technique is a result of collaboration among researchers in several scientific disciplines, said co-lead author Silvia Vignolini, professor in Cambridge's department of chemistry.

“I am particularly proud of this work not only for the potential applications, but also for its fundamental point of view,” Vignolini told Seeker. “It is the first time that the structural coloration of any living organism has been genetically controlled.”

RELATED: We Could Be on the Threshold of a New Era of Color Science

To develop the new process, researchers compared the genetic information, optical properties, and anatomy of multiple natural and mutated bacterial colonies. By mixing and matching elements of different colonies, researchers found they could generate different optical effects.

For instance, researchers changed the genetics of one particular colony to alter the way individual bacteria move around. That change altered the geometries within the colony, which in turn changed the color from green to blue, then eventually to red. The research team was also able to create brighter or duller coloration, or even make the color disappear entirely.

“We mapped several genes with previously unknown functions and we correlated them to the colonies' self-organizational capacity and their coloration,” senior author Colin Ingham, CEO of Hoekmine BV, said in a statement released with the new research.

As to practical applications of the technology, any large-scale deployment is still several years away. But Vignolini said the time may come when such “living paints” are available in car dealership showrooms and on hardware shop shelves.

“The future is open for biodegradable paints on our cars and walls, simply by growing exactly the color and appearance we want,” she said.

Interestingly, one of the first consumer products might be aimed at kids, Ingham said.

"We did actually consider making a sort of science kit, maybe for schools, but it's not yet available,” she said. “The bacteria are not harmful and pretty robust.”

RELATED: The Color of Your Clothing Could Affect the Behavior of Animals

The living paints might have other useful applications, too. Because the living bacteria can react to other molecules, they could be used to make materials and surfaces that change color under designated circumstances.

“I think a possible application would be to get something that exploits the unique sensing ability of these colonies,” Vignolini said. “We could genetically engineer them to detect pollution or specific molecules.”

Considering the paints and coatings are quite literally alive, one question remains. This may be indelicate — to the bacteria, anyway — but what happens when the bacterial colonies die?

“They keep the color as long as they are alive, and we can add some fixatives so that when they are dead they do not degrade,” Vignolini said. “In that case, the colors last even if the bacteria are dead.”
Shine on, brave bacteria. You shall not be forgotten.