CaliToday (07/11/2025): A revolutionary "survival-of-the-fittest" technique tricks microbes into producing 1,000 times more of a rare pigment, paving the way for new color-changing materials.
 |
| Extreme close up of Octopus eye and skin texture, macro underwater photography |
Octopuses, squid, and other cephalopods are the undisputed masters of disguise. They possess a "superpower" that allows them to seemingly vanish into any background, a feat accomplished by a complex, psychedelic skin that can change color and texture in an instant.
Now, scientists at the University of California San Diego have taken a major leap toward recreating this marvel of nature. A research team has successfully bioengineered common bacteria to mass-produce xanthommatin, one of the key pigments that gives cephalopods their mesmerizing color-shifting abilities.
This breakthrough, published in Nature Biotechnology, not only unlocks the secrets of octopus camouflage but also introduces a powerful new method for sustainable "microbial manufacturing."
A Pigment That Was Impossible to Get
Until now, xanthommatin has been notoriously difficult to acquire. Harvesting the pigment directly from animals is impractical and inefficient. Synthesizing it in a lab is equally complex and yields vanishingly small amounts. This bottleneck has prevented scientists from truly studying how the pigment functions and, more importantly, how humanity might learn to mimic it.
"We've developed a new technique that has sped up our capabilities to make a material, in this case xanthommatin, in a bacterium for the first time," says senior author Bradley Moore, a marine chemist with Scripps Oceanography and UC San Diego.
"This natural pigment is what gives an octopus or a squid its ability to camouflage—a fantastic superpower and our achievement to advance production of this material is just the tip of the iceberg."
The 'Growth-Coupled' Trick
To solve the production puzzle, the researchers didn't just ask bacteria to make the pigment—they forced them to.
Lead author Leah Bushin, who led the study in the Moore Lab, explains that microbes are "practical organisms" and "don't like to waste their meager resources making products that aren't strictly necessary for their survival."
So, Bushin and her colleagues engineered "an offer they couldn't refuse" using a new method they call "growth-coupled biosynthesis."
Here’s how the ingenious "trick" works:
A "Sick" Cell: The team genetically engineered "sick" bacteria that lacked a critical survival pathway.
A Life-or-Death Bargain: They modified the bacteria's DNA so that the only way the microbes could grow and survive was by producing two specific compounds.
The Two Products: The first compound was the target, xanthommatin. The second was formic acid, which the engineered bacteria desperately needed as fuel to live.
The system was designed as a perfect feedback loop: for every molecule of xanthommatin the bacteria produced, it also produced one molecule of formic acid. To get the fuel (formic acid), they had to make the pigment (xanthommatin).
"We made it such that activity through this pathway, of making the compound of interest, is absolutely essential for life," Bushin says. "If the organism doesn't make xanthommatin, it won't grow."
 |
| Bacteria producing xanthommatin on a petri dish in the lab. (Leah Bushin/Scripps Oceanography) |
An Overnight Success
The team didn't have to wait long to see if the gamble paid off.
"It was one of my best days in the lab," Bushin recalls. "I'd set up the experiment and left it overnight. When I came in the next morning and realized it worked and it was producing a lot of pigment, I was thrilled. Moments like that are why I do science."
The results were staggering. The new method yielded up to 3 grams of pigment per liter of medium. This doesn't sound like much, but it's a monumental leap from the approximately 5 milligrams per liter produced by other methods an efficiency boost of up to 1,000 times.
To further enhance this, the team used adaptive laboratory evolution and bioinformatics tools, optimizing the microbes to synthesize the pigment from a single, simple nutrient source like glucose.
A New Era of Biomanufacturing
Beyond finally giving scientists enough pigment to study cephalopod camouflage and potentially develop new biomimetic materials the method itself may be the most significant part of the discovery.
This "growth-coupled" approach could be applied to persuade bacteria to sustainably produce other valuable chemicals, such as medicines, biofuels, or bioplastics, that are currently expensive or environmentally costly to create.
"This project gives a glimpse into a future where biology enables the sustainable production of valuable compounds and materials through advanced automation, data integration, and computationally driven design," says co-author Adam Feist, a bioengineer at UC San Diego.
"Here, we show how we can accelerate innovation in biomanufacturing by bringing together engineers, biologists, and chemists using some of the most advanced... techniques to develop and optimize a novel product in a relatively short time."