How to use bacteria for good

Imagine that an earthquake creates cracks in San Francisco's Bay Bridge. Instead of collapsing, the bridge's girders patch up their own fractures.

That's the vision behind an unlikely collaboration between an industrial designer and a microbiologist who think they’ve found the key to creating materials with some of the characteristics of life.

"Ultimately, we want material that is capable of repairing itself," said David Bramston, a senior lecturer in product design at the University of Lincoln in the United Kingdom. "That led us to slimes and jellies."

The slimes he's referring to are known as biofilms, which are three-dimensional colonies of bacteria that secrete a starchy covering that protects the tiny creatures from predators, UV radiation and antibiotics. If scientists could weave them into building material or fabric, the result could be self-regenerative structures and even clothing.

The plaque on your teeth is a biofilm. So is the slime under rocks. Biofilms kill cystic fibrosis patients, and they create problems for engineers by clogging oil pipelines. Most scientists are trying to get rid of biofilms. After all, they are 1,000 times more resistant to antibiotics than free-floating microbes. And the National Institutes of Health estimate that biofilms account for more than 80 percent of microbial infections in the human body.

Bramston said microbiologists "are intrigued that an industrial designer is flying around the world saying, 'I like biofilms.'"

He believes that some biological jujitsu could turn biofilms' virulence into a force for good. Films large enough to see are the best candidates.

"In papermaking facilities, the pulping liquor contains a lot of organic carbon, which grows huge biofilms," said Paul Sturman, a senior research engineer at the Center for Biofilm Engineering, a National Science Foundation-funded engineering research center at Montana State. "The bacterial colony is so thick that you can pick it up and hold it in your hand."

These bacterial colonies function as a unit, cooperating and communicating to stay alive. They have entirely different properties from free-floating, so-called planktonic, bacteria.

"The genes that are expressed when they're in a biofilm are very different from the genes expressed in a free-floating state," said Derek Lovley, a professor of microbiology at the University of Massachusetts at Amherst.

Those genetic differences have startling repercussions.

Bramston and his collaborator, Ron Dixon, head of forensic and biomedical sciences at the University of Lincoln, have focused their research on the actual material that their bacterial strain, Pseudomonas aeruginosa, often grows on: slag from the sewers of England. By studying the surface contours of the slag, Bramston wants to learn to grow better biofilms that he can turn into usable material.

The researchers are also broadening their search for lifelike materials outside of slimes. One promising area they’ve identified is microcapsules, which were used by Scott White of the University of Illinois to create a self-repairing plastic. His group inserted tiny beads of "healing agent" into a material. The agent is activated by impact, like a glow stick, to patch up any fractures.

Bramston and Dixon even believe they might contribute to efforts in preventing unwanted biofilms. Using industrial-design materials-research techniques, Bramson said, he's found that smoother surfaces could actually aid biofilm formation, a retrograde thought in the microbiological world. So, rougher surfaces -- counterintuitively --might be better in places where you don't want biofilms, like your kitchen or a hospital.

"Biofilms are still mysterious in many ways," Sturman said. "I think anybody studying them would agree that there is a great deal to learn about how they interact with each other and the mechanisms they use to survive."


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