Giving Trees Probiotics Helps Them Clean Up Toxic Soil

Trees have always had the ability to capture and remove pollutants from both the air and the soil. However, they never had enough power to completely clean the soil of all toxic chemicals. Until now. Studies are being conducted at a superfund site where scientists are testing a new theory. A probiotic is a substance that stimulates the growth of microorganisms, especially those with beneficial properties. Like humans, it has been found that trees can also benefit from probiotics.


Researchers from the University of Washington have begun conducting the experiment by creating poplar trees fortified with a probiotic. The goal of the experiment was to see how well the trees could glean up ground water contaminated with trichloroethylene. Trichloroethylene is an industrial solvent as well as a known carcinogen. Trichloroethylene does not naturally occur in soil, however it is found in areas that have been contaminated by industrial waste. Removing this from the ground is normally a long and expensive project.

greeningz - poplar trees

Using trees to clean up soil in contaminated area is not a new idea. It has been used many times before. However, after absorbing the toxic chemicals many tree’s growth is stunned or the trees die. With this new probiotic, neither occurs. On the contrary, the trees grew larger than the control trees as well as pulled out more trichloroethylene from the soil.

In order to find a successful probiotic, researchers visited a site in the midwest where poplar trees were already living in trichloroethylene contaminated soil. They took samples from several trees and isolated different microbes from each one. The microbes were then place in a flask with high levels of trichloroethylene. After testing many different microbes, they were able to find one that worked the best.


Sharon Doty is a University of Washington professor, in the School of Environmental and Forest Sciences, as well as a co-author of the study. Doty said, “These results open the door. We have known about this process for a long time from our laboratory research, but it hasn’t been used in practice because there were no field results. Now, engineering companies can start using this in real life.”