Wood's Research Solves Problems,
But Doesn't Exactly Get the Bugs Out
December 13, 1999
rofessor Thomas Wood is on the verge of solving part of a problem that costs the U.S. electric power industry upwards of $10 billion annually.
The problem is corrosion, and it's not just the power industry's problem. It's yours, too. A major cause of catastrophic breakdowns, especially in hydroelectric facilities, corrosion drives up the cost of electricity for all consumers by at least 10 percent.
But Wood's solution isn't more durable metals. It's bacteria. Armed with a grant from the Electric Power Research Institute, of Palo Alto, Calif. - and with an idea that he began to explore after a 1994 tennis match with a materials scientist who was working on corrosion problems - Wood has bred strains of microbes that can protect metal from corrosion.
"Like the surfaces of practically everything, the metal surfaces at power plants become colonized by microbes over time," says Wood, an associate professor who joined the Department of Chemical Engineering in 1998. "The microbes eventually merge to form what we call a biofilm, like the slimy coating on rocks you find in a pond. Usually these biofilms are damaging. They can corrode most metal alloys, even metals such as steel and aluminum that are corrosion-resistant."
But, Wood has discovered, some microbes can have the opposite effect: some bacteria can dramatically decrease the corrosion rate of metals by consuming oxygen in the water that would cause oxidation - rust. And Wood's microbes have an added value. They release an antimicrobial substance that is not harmful to themselves, but inhibits harmful bacteria from taking up residence.
Wood's microbes have proven so effective in tests, that he and the EPRI are currently developing a patent. With two years already invested in the cumbersome patenting process, he estimates it will be many more before his microbes hit the market. In the meantime, he has pressed ahead with other applications of the same technology. One of those applications could save your life some day.
Antibiotics of the Future
Wood's research began with his exploration of what he calls single cell altruistic behavior. Viruses attacking some cells actually appropriate the cells and turn them into replicators, which produce hundreds of new viruses that advance the assault during an infection. But Wood discovered that those cells also contain a gene which causes them to commit suicide by producing a lethal protein when they are under microbial attack. They kill themselves for the good of the whole.
When it is switched on, this gene becomes an entirely new weapon in man's ageless struggle against microbes. If tests that he will conduct in his laboratory in January are successful, he predicts it could result in a whole new class of antibiotics within five years.
An advantage of these protein-based antibiotics, says Wood, is their adaptability. "Bacteria mutate constantly," he says, noting that the current antibiotics - which have lost some of their effectiveness, as bacteria have adapted to become resistant - would become fully effective once again if we could only avoid using them for a decade. The protein-based antibiotics are much more manageable, however, and new variations can be created very quickly. "With protein-based antibiotics, you have another tool to help you stay ahead of the bacterial mutations," he predicts.
Trees of Tomorrow
The products have tremendous utility, because they don't burn or explode. But neither do they break down. Remarkably durable, they require hundreds of years to decompose. Until the 1950s, they were routinely disposed of by simply washing them into the soil. Now they pollute aquifers all over America.
But Wood thinks he knows how to get them out of the water. He has engineered an enzyme that actually recycles these products, consuming and oxidizing them. And he has also found a way to get the enzyme to the chemicals, locked in aquifers anywhere from 10 to 40 feet underground.
The answer is trees - specifically poplars, which reach maturity quickly and consume up to 50 gallons of water daily. In his laboratory, Wood has discovered that when the roots of saplings are dipped into solutions containing the beneficial bacteria that produce the enzyme, the saplings and the bacteria bond into a symbiotic relationship. The trees become hosts for the bacteria and when their roots reach the polluted aquifers, they quickly convert the dangerous chlorinated solvents into harmless byproducts.
Already, in his laboratory, a small forest of prototype plants have proven that the technology works.
Beyond these inventions, Wood envisions a wide range of other applications for the basic science that is the engine of his laboratory, including increasingly effective bacteria that can recycle the methane gas released from waste landfills. He believes he has only scratched the surface of the problems that can be solved with bioengineered bacteria. "I'm very optimistic about the future," he says.