Endophyte-Assisted Phytoremediation of TCE, PAHs, TNT, and Arsenic

Phytoremediation is an effective technology for remediation of a wide range of environmental pollutants.  However, when the pollutant is at phytotoxic concentrations, a modified technology is required.  Endophytes are microorganisms that live within plants that can provide multiple benefits to the plant including increased nutrient acquisition and growth, and improved stress tolerance.  In addition, some strains of endophytes have the capacity to degrade or otherwise reduce the toxicity of xenobiotics.  We have isolated endophytes that degrade TCE, PAHs, and TNT, and addition of the strains to plants results in improved plant health on normally phytotoxic levels of these pollutants.  The genomes of the TCE and PAH degrading strains have recently been sequenced, providing insight into mechanisms by which the strains can improve phytoremediation.  Using fluorescent microscopy, we have demonstrated that multiple strains can co-colonize poplar, providing the potential to equip plants for sites polluted with multiple classes of chemicals.  A field trial of the TCE-degrading strain with poplar trees is currently underway.  In addition to the endophytes capable of degrading organic pollutants, we have recently isolated an arsenic-tolerant endophyte that reduces the phytotoxic effects of arsenic in inoculated Arabidopsis seedlings.  Endophyte-assisted phytoremediation is an important technological advance enabling this green technology to be utilized on a broader spectrum of contaminated areas.