Chemical-munching superbug cleans up polluted water

Hoovers Online ^ | July 3, 2003

[gitmo]

One of the biggest environmental headaches is vinyl chloride, a toxic compound which can seep into water tables from chemical plants or industrial users.

Cancer-causing and fertility-damaging, this organic chloride is the main ingredient in everyday PVC products such as plastic furniture, car upholstery, pipes and insulation for electrical cables.

Chemical firms around the world are under pressure from authorities to tackle aquifer pollution from this highly useful but dangerous substance.

But the process, sometimes entailing the removal of contaminated soil where there are major spills, is long, expensive, sometimes impracticable and often likely to inflict environmental damage.

Now, say a group of scientists, there's an answer.

It is a disc-shaped bacterium that gobbles up vinyl chloride and another toxic derivative, dichloroethene. It dies when its source of food runs out. And, its discovers say, it's quite harmless to humans and the environment.

The remarkable bug -- isolated after a gruelling years-long quest in the realm of underworld bacteria -- has been dubbed BAV1 by its discoverers, a team led by German microbiologist Frank Loeffler, assistant professor at the Georgia Institute of Technology in Atlanta.

BAV1 is anaerobic, meaning that it lives in an oxygen-free environment, and metabolises vinyl chloride and dichloroethene to provide its energy. The only significant by-products from this are the non-toxic hydrocarbon gas ethylene and harmless inorganic chloride.

"These organisms are highly specialised. They can only grow in the presence of the contaminant, and when the contaminant is gone, they disappear," Loeffler told AFP in a phone interview.

"We have been working with this organism for years and we have absolutely no evidence that this organism has any negative impact on humans or wildlife."

After finding how the bug worked in lab conditions, Loeffler's team set out on devising ways in which it could be brewed in large quantities as well as a means of delivering it into the water table to clean up the pollution.

The bacteria are injected below ground, suspended in a liquid. They then attach themselves to sand or particles in the soil, creating a "biofilm" that traps the vinyl chloride in the water which slowly flows through this soft rock.

The discovery, described in Thursday's issue of the British weekly journal Nature, was tested a pilot site in Michigan that measured about 25 square metres (264 square feet) in area and seven metres (22.75 feet) deep.

"We completely removed the contaminants in this plot in six weeks. It was very, very successful," Loeffler said.

The cleanup was so impressive and BAV1 so easy to use that the bug has now been patented and a commercial company has started to market it, Loeffler says.

Because the bacteria tend to adhere to particles, they do not shift to other parts of the aquifer -- they stay in the area where they have been injected, acting rather like a filter, strung out across the water flow.

Bioremediation -- using bacteria to clear up chemical or nuclear sites -- has been a holy grail of biologists, chemists and environmentalists for a number of years.

But only a small number of discoveries has reached the market place. Many initially promising finds turn out to be less effective than thought; sometimes they may rouse environmental concerns; and at other times, bugs turn out to be fragile and difficult to use in the world outside the laboratory.

Vinyl chloride is soluble, which means that it can integrate into the water supply directly or when its parent chemicals, tetrachloroethene and trichloroethene, enter the water and are broken down.

Vinyl chloride evaporates rapidly in the air and is biodegraded underground by bacteria, but in high concentrations runs a major risk of ending up in drinking water.

[gitmo]

Environmentalists are going to be pizzed.

[LizardQueen]

If this thing got into the house plumbing would it eat the pipes?

LQ

[gitmo]

I don't know.
But I'm pretty sure you can grow these critters in the toilet, and you won't have to flush.