Endophyte-Assisted Phytoremediation: Genomic Analysis to Successful Field Trial

Phytoremediation technologies can be improved with the utilization of effective microbial endophyte strains. A natural TCE-degrading endophyte was isolated that rapidly dehalogenates TCE, releasing chloride ion. In a 3-year field trial at a TCE ground water plume EPA-designated Superfund site, poplar trees inoculated with the endophyte strain had enhanced survivability and growth compared to mock-inoculated control trees. The inoculated trees exhibited increased chloride exudation in the rhizosphere, and leaf tissue analysis confirmed enhanced TCE degradation. Genomics analysis of the Enterobacter strain did not reveal any of the known genes involved in TCE degradation. A TnSeq approach is underway to determine the genes required for TCE metabolism in this strain. In addition to the endophytes capable of degrading organic pollutants, we isolated arsenic-tolerant endophyte strains that may reduce the phytotoxic effects of arsenic in host plants, and are investigating a potential role for extracellular polymeric substances (EPS) in the detoxification of arsenic by endophytes. Endophyte-assisted phytoremediation is an important technological advance enabling this green technology to be utilized on a broader spectrum of contaminated areas.