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Cephalopods like squid, octopuses, and cuttlefish are remarkably sneaky—they imitate their marine environments to evade both predators and prey. These expert camouflage skills have intrigued scientists as long ago as 350 B.C., when Aristotle took interest in octopuses’ shifting hues. We now know that this clever camouflage process involves a color-changing pigment called xanthommatin, which is also what gives some insects like butterflies their vibrant colors.
Xanthommatin could offer major benefits for humans, too. It could be harnessed to make hue-shifting displays and dyes, for example, and more effective sunscreen. The pigment absorbs ultraviolet light throughout the visible spectrum and has been found to enhance the effectiveness of chemical sunscreens. (It could also be less harmful for marine environments.)
So researchers have spent decades trying to produce xanthommatin in the lab and take advantage of these tantalizing properties. Now, one team of scientists says they’ve found a way to churn out significant amounts of xanthommatin with the help of a modified microbe.
Read more: “Nature’s Invisibility Cloak”
Thanks to some genetic tweaks, these scientists were able to prompt a bacterium to produce up to 1,000 times more xanthommatin than other genetic engineering methods, as reported in a recent paper in Nature Biotechnology.
“We needed a whole new approach to address this problem,” said lead author Leah Bushin, a chemical biologist formerly at the University of California, San Diego’s Scripps Institution of Oceanography, in a statement. “Essentially, we came up with a way to trick the bacteria into making more of the material that we needed.”
To fool this microbe, Bushin and her colleagues tied its survival to manufacturing xanthommatin. They modified the genes of a soil-dwelling bacterium called Pseudomonas putida, forcing it to create both xanthommatin and a chemical called formic acid—which, in turn, propelled the cell’s growth. This spurred “a self-sustaining loop that drives pigment production,” according to the statement.
The team also pinpointed the genetic mutations that allowed these engineered microbes to pump up the volume, and selected for strains that only require a single carbon source. These key details make xanthommatin production as efficient and sustainable as possible.
It’s still early days for this potential bacterial boon, but the paper authors say they’ve received interest from cosmetics companies who’d like to incorporate the substance into natural sunscreens. Xanthommatin might also make its way into color-changing paints for consumers or environmental sensors. But it’s up to these mighty microbes and whether they’re up to the demand. 
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Lead image: Mike Bartick / Ocean Image Bank
