Heat-loving marine bacteria, such as Thermus aquaticus and Thermus thermophilus, have been known to thrive in harsh environments, including high temperatures. While these bacteria are not typically associated with asbestos detoxification, they do have some characteristics that could potentially help in the process.
Because of their strength and resistance to heat and fire, as well as their low electrical conductivity, asbestos materials were once widely used in homes, buildings, automobile brakes, and many other built materials. Unfortunately, asbestos exposure through small fiber particle inhalation has been shown to be highly carcinogenic.
For the first time, University of Pennsylvania researchers have demonstrated that extremophilic bacteria from high temperature marine environments can be used to reduce the toxicity of asbestos. The study was published in the American Society for Microbiology journal Applied and Environmental Microbiology.
D. palaeochoriense has also been shown to mediate electrical charge transfer within the iron in asbestos without changing its mineral structure. Based on this finding, the bacterium could be used to treat asbestos toxicity by removing iron.
Pérez-Rodrguez
Much of their research has concentrated on the use of the thermophilic bacterium Deferrisoma palaeochoriense to remove iron from asbestos minerals via anaerobic respiration. “Iron has been identified as a major component driving the toxicity of asbestos minerals, and its removal from asbestos minerals has been shown to decrease their toxic properties,” said Dr. Ileana Pérez-Rodrguez, Assistant Professor of Earth and Environmental Science at the University of Pennsylvania.
D. palaeochoriense has also been shown to mediate electrical charge transfer within the iron in asbestos without changing its mineral structure. According to Pérez-Rodrguez, doing so may improve the electrical conductivity of asbestos.
Based on this finding, the bacterium could be used to treat asbestos toxicity by removing iron. Alternatively, the new electrical conductivity properties may allow for the reuse of treated asbestos for that purpose.
As with iron, the fibrous silicate structures of asbestos are also carcinogenic. Removal of silicon and magnesium from asbestos has been shown to disrupt its fibrous structure. The investigators tested the ability of the thermophilic bacterium Thermovibrio ammonificans to remove these elements from asbestos minerals by accumulating silicon in its biomass in a process known as biosilicification.
T. ammonificans accumulated silicon in its biomass when exposed to “serpentine” asbestos, which has curly fibers, but not when exposed to “amphibole” asbestos, which has straight fibers, according to Pérez-Rodrguez. This distinction, as well as the various amounts and types of elements released during microbe-mineral interactions with various types of asbestos, “highlights the difficulty of approaching asbestos treatments as a one-size-fits-all solution, given the unique chemical compositions and crystal structures associated with each asbestos mineral,” said Pérez-Rodrguez.
Overall, these experiments promoted the removal of iron, silicon and/or magnesium for the detoxification of asbestos in a superior manner as compared to other biologically mediated detoxification of asbestos, such as via fungi, said Pérez-Rodríguez. However, further analysis will be required to optimize asbestos treatments to determine the most practical methods for the detoxification and/or reuse of asbestos as secondary raw materials.
