Trees growing on the Silicon Valley test site at the start of their third season. The second and fourth trees (from left) have been given microbes and are growing faster than the poplars with no microbes (first and third trees, from left). Source: Michael Blaylock/Edenspace Systems CorporationTrees growing on the Silicon Valley test site at the start of their third season. The second and fourth trees (from left) have been given microbes and are growing faster than the poplars with no microbes (first and third trees, from left). Source: Michael Blaylock/Edenspace Systems Corporation

Many people subscribe to the concept of probiotics, live micro-organisms which, when administered in adequate amounts, confer a health benefit on the host. Now researchers have demonstrated the use of probiotics in fortifying the power of trees to phytoremediate environmental contamination.

University of Washington researchers analyzed poplar wood obtained from a site in the Midwest where trees were already growing in trichloroethylene (TCE)-contaminated soil. After grinding down small samples of the trees and isolating over a hundred different microbes, each strain was then placed in a flask containing high levels of TCE. The microbe that eliminated nearly all of the TCE in its flask as selected for additional testing.

The researchers used this ubiquitous and toxic chemical to examine the ability of poplar trees inoculated with microbes to clean up groundwater in a Superfund research area in California’s Silicon Valley after it had subsequently flowed into NASA Ames Research Center complex. Rows of young poplar trees, some infused with the microbe and others without, were planted on a field above a known groundwater plume contaminated with TCE.

After a year, the trees given the microbe were bigger and healthier than those with no special treatment. Inoculated trees were still more robust after three years, and a sample of tree trunks revealed greatly reduced levels of TCE inside the trees.

Groundwater samples taken directly downstream from the test site showed much lower levels of the toxin, compared with higher levels up-gradient.

Researchers from Phytoremediation and Phytomining Consultants United, Missouri University of Science and Technology, Tuscia University in Italy, Edenspace Systems Corporation, Environmental Forestry Consultants and Earth Resources Technology also participated in this study.

To contact the author of this article, email shimmelstein@globalspec.com