Color from Nature

UC Davis graduate student Farzaneh Alihosseini holding a vial of the colorant

Courtesy of Farzaneh Alihosseini

Friday, June 27th, 2008--

Bright red workout clothes with a built-in germ-fighter--coming soon to a store near you? Absolutely, if researchers at the University of California, Davis have anything to say about it. They’ve found a strain of marine bacteria that produces large amounts of red pigment that can color clothing and guard against harmful bacteria. “We grow the micro-organisms and they produce the colorants,” says Gang Sun, Professor of Textiles and Clothing at the University of California, Davis, and research team leader.

The scientists were hunting for organisms that produce natural colorings. They tried mushrooms, but the fungi grew slowly, so although the color they made was good, there just wasn’t enough of it. Then they set their sights on one kind of marine bacteria, Vibrio sp. “These bacteria are known to produce a very red color in very large quantities in a very short time,” says Sun.

The researchers plucked the bacteria from sediment on the shore of Eel Pond in Woods Hole, Massachusetts. Then they brought the bacteria into the lab and gave them enough food and an ideal habitat so the micro-organisms could grow and thrive--and make a lot of pigment. They tested the dye on a dozen materials and found that it worked well on several, particularly wool and silk.

Sun and his colleagues aren’t exactly sure why the bacteria make the brilliant red dye, but they suspect it has something to do with protection. The pigment, a compound called prodigine, has antibacterial properties, too.

Sun thinks the pigment gives the bacteria built-in protection against other harmful micro-organisms. Coloring a material with the pigment passes on that anti-microbial protection. Lab tests showed that most of the dyed fabrics they tested had the ability to kill both E. coli and S. aureus. The fabrics that absorbed more dye, such as wool, were better germ-fighters than those fabrics, such as cotton, that didn’t take up as much color, according to Sun. The researchers are working to increase that protection, so more fabrics will provide more protection against more germs.

Eventually, says Sun, they hope this pigment can be used to make protective uniforms for hospital workers or the military. For now, it can be used to give workout wear--garments like underwear, socks, and t-shirts--a bright, long-lasting red color, along with some germ-fighting properties.

But what if red’s not your color? “It’s a colorful world,” says Sun, who thinks this pigment will be a building block for other colors. His team hopes to chemically modify the pigment to create a whole spectrum of color.

And the dye could also have other uses. For instance, it might be good for making make-up—say, a rouge that gives cheeks a rosier glow. The Davis researchers have heard from a cosmetics company interested in using the dye as a natural alternative to some of the ingredients used in make-up today.

This research is published in a recent issue of the American Chemical Society journal, Biotechnology Progress.

--Karin Vergoth