Biotechnology in fight against pollution

SAN FRANCISCO: On the site of a former hat factory in Danbury, Connecticut, a stand of genetically altered cottonwood trees sucks mercury from the contaminated soil.

Across the continent in California, researchers use transgenic Indian mustard plants to soak up dangerously high selenium deposits caused by irrigation of the nation's bread basket. Still others are engineering trees to retain more carbon and thus combat global warming.

The gene jockeys conducting these exotic experiments envision a future in which plants can be used as an inexpensive, safer and more effective way of disposing of pollution.

``Trees are really made for this ... we just have to trick them to do what we want them to do,'' said Richard Meagher, whose University of Georgia students went to Danbury in 2003 as part of the most advanced, open-air experiment in the United States involving trees genetically engineered to eat pollution.

Biologists for decades have been trying to exploit the genetic mechanisms that let microscopic bugs survive in polluted places where most living things die.

Indeed, the 1980 landmark U.S. Supreme Court case that allowed the so-called ``patenting of life'' that launched the biotechnology industry centred on bacteria genetically engineered to clean oil spills.

But simply dumping engineered bugs on polluted sites has its dangers and drawbacks. Elements like mercury cannot be broken down into harmless bits like oil, so researchers have turned to engineering plants to draw pollutants out of the ground.

Mr. Meagher uses genes from E. coli that enable the common bacterium to live amid mercury. He has spliced them into a variety of plants in the laboratory, where he says his results are dramatically positive.

But proving genetic engineered plants work outside the lab is the real challenge — and Danbury, which at the turn of the last century reigned as the hat-making capital of the world, was a natural destination for his team.

Animal pelts in the town's many factories were softened in mercury baths, and the resulting waste was dumped outside. Only later did residents understand how mercury attacks the central nervous system. By then, many longtime factory workers had suffered from the ``Danbury shakes.''

Mr. Meagher's team planted about 45 engineered cottonwood trees in a polluted lot. The trees are expected to treat the mercury as a nutrient and draw the toxic element for the soil with their roots.

Some of the mercury is expected to vaporise into the air while most is stored in the tree.

After several years of growth, the trees will be cut down and incinerated.

Mr. Meagher expects to see results from the Danbury experiment later this year. He figures hundreds of trees per acre would need to be planted to be effective. But if his removal method works, the cost of cleaning an acre of mercury-laced soil will plummet from about $2 millions to $200,000, Mr. Meagher estimates.

He agrees with critics who argue that his solution is not ideal — but he says the trees beat the current clean-up method of digging out contaminated sites and dumping the tainted soil in toxic dumps.

He said he was also hoping to someday deploy genetic engineered trees in northern India and Bangladesh where arsenic poisoning is rampant. Drinking water throughout the region has been contaminated by soils polluted naturally and by spills from factories. — AP

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