Angewandte Chemie International Edition
Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
For full article and contact information, see Angew. Chem. Int. Ed. 2003, 42 (02), 219 - 222
Fungi to Fight Asbestos
Bio-decontamination of asbestos-contaminated soils -
fungi bind and deactivate asbestos fibers
The use of asbestos is now widely forbidden and most contaminated buildings have been cleaned up. However, there is another source of danger that is more difficult to remove: naturally occurring asbestos-containing minerals, which were previously used as a source of the material. The areas around these abandoned asbestos mines, for instance some Alpine regions, are broadly contaminated with finely divided asbestos. Removal is thus not possible. A team working with Bice Fubini and Silvia Perotto in Turin is now proposing to deactivate the asbestos instead. Fungi are to lend a hand.
The idea stems from one of the components of most asbestos-containing minerals: iron ions. On their own, iron ions are harmless and are even necessary to our lives, as a component of hemoglobin, for example. However, under the conditions on the surface of asbestos fibers, these peaceful iron ions become highly unpleasant. It has been found that they play a major role in the toxicity of asbestos fibers; they seem to be critical in the generation of the free radicals that damage the genetic information of cells, which can result in cancer. Removal of the iron from the surface of asbestos drastically reduces this effect.
Fungi that are present in soil, thought the Italian researchers, could take on the job of removing the iron. It is known that certain types of fungi produce iron-binding substances, which transport the iron and store it in cells. Additionally, owing to their filament network (mycelium), the fungi can spread widely, permeating large volumes of soil.
The researchers tested a series of different fungi and identified several types that get along swimmingly in the company of blue asbestos - the most dangerous asbestos mineral. The fungi attach to the asbestos fibers through their myceliar filaments and then proceed to busily extract the iron from them. In this process, the asbestos fibers are bound together, thus preventing them from spreading any further. As expected, the removal of iron causes a change in the surface structure of the fibers. Now inactive, this form might be no longer carcinogenic. "On the basis of our findings, it could be possible to develop a process for the bio-decontamination of asbestos-contaminated soils," hopes Fubini.