HALLE-WITTENBERG, Germany, Jan. 22 (UPI) -- Scientists said Wednesday bacteria found in sediments of a polluted German river can digest dioxin, a chemical contaminant linked to cancer and other diseases.
The researcher team said the bacteria, discovered in the Spittelwasser River, break down dioxin into a less toxic chemical that easily can be degraded.
This is the first time a bacterium has been identified that can degrade dioxin and the discovery will allow researchers "to evaluate the power of natural attenuation processes for the reduction of dioxin toxicity," said researcher Michael Bunge of Martin Luther University. The finding by Bunge and his colleagues is reported in Wednesday's issue of the journal Nature.
Dioxin is a byproduct of industrial processes involving chlorine, including waste incineration and production of paper and herbicides. Dioxin also was a contaminant in the notorious defoliant Agent Orange, used by the U.S. troops during the Vietnam War.
Chemical workers exposed to high levels of dioxin have developed cancer, according to the National Institute of Environmental Health Sciences. High dioxin exposure also can lead to reproductive and developmental problems, increased risks of heart disease and diabetes, according to NIEHS.
The bacteria, called Dehalococcoides CBDB1, are anaerobic -- meaning they only live in the absence of oxygen, unlike most other organisms. The bacteria attack the chlorine atoms in dioxin.
"During the attack of dechlorinating bacteria, most of the chlorine atoms are removed," Bunge told United Press International in an e-mail.
Dehalococcoides CBDB1 is said to "dehalorespire," meaning the bacteria gain energy from the chlorine atoms. Reducing the number of chlorine atoms makes the chemical less toxic and means other bacteria can degrade it. Discovering such a bacterium is good news, said Eugene Madsen, a Cornell University microbiologist.
"Any time a new organism is discovered it has great potential. It adds to the knowledge we have about microorganisms and it adds to the tools that can be applied by biologists and engineers to effect environmental clean up," he told UPI.
Madsen was cautious, however, about the impact this newly discovered organism might have on dioxin decontamination of the environment.
Bunge also pointed out there are limitations to where the organism could be effective, since it can only live in the absence of oxygen.
"Therefore, a potential (future) application of Dehalococcoides strains will be restricted to anaerobic habitats such as sediments of rivers, anaerobic ground aquifers or deeper layers of soil," Bunge noted.
Dioxin, of which there are scores of different forms, can pose other cleanup problems, Madsen said. "Dioxins are notoriously good at binding to soils and clays," he said, thus making it difficult for bacteria to work on them.
A good deal of research remains to understand how to stimulate the bacteria growth in contaminated environments, and to understand its physiology, Bunge said.
(Reported by Harvey Black, UPI Science News, in Madison, Wis.)
