Endophyte-Assisted Phytoremediation of Arsenic

Research Sponsored By: Edenspace Systems Corporation
Principal Investigator: Sharon Doty
Project Description
Edenspace Systems Corporation, in collaboration with the laboratory of Sharon Doty at the University of Washington (UW), aims to develop a novel phytoremediation system for arsenic-contaminated soils. Unlike most organic contaminants, heavy metals persist in the environment and cannot be biologically degraded in situ. Phytoextraction employs the capability of some plants to accumulate toxins in their above ground foliage which can then be harvested, removing the pollutants from the site. An important first step in a successful phytoextraction strategy involves plant selection for biomass production and metal accumulation capacity. Shrub willows (Salix spp.), with their rapid growth rates, high biomass production, tolerance to coppicing and extensive root systems, are strong candidates for phytoextraction involving arsenic-contaminated soils. Previous studies of willows have yielded promising early results in their ability to grow on soils with high concentrations of heavy metals, as well as the ability to accumulate arsenic. However, even in plants demonstrating tolerance, elevated levels of heavy metals act as phytotoxins, and as a result limit the effectiveness of remediation efforts by reducing biomass accumulation and increasing rates of morbidity and mortality. The use of endophytic bacteria and fungi may provide a solution to this problem by promoting plant survival in contaminated soils or participating in the detoxification of the contaminants in planta. Endophytic bacteria were isolated from plants growing in the arsenic-contaminated soils from the smelter in Tacoma. These microbial strains grow in high levels of arsenic and may have the necessary detoxifying and sequestering capabilities. For this project, we will characterize the endophytes and test if phytoremediation can be enhanced when the plants are colonized by these natural bacteria.