Alteration and Remediation of Asbestos Fibers: Current state-of-the-art for treatment of asbestos- contaminated sites is to move the asbestos and/or cap the site. The proposed research examines whether chemical alteration of asbestos particles by plants and/or fungi, either directly or indirectly via plant exudates or fungal metabolites, may be useful for bioremediation of asbestos-contaminated sites. The project is motivated by evidence that fungi (Fusarium oxysporum and Verticillium leptobactrum) can remove Fe atoms from asbestos particles, rendering them less toxic. We will target plant species that are known to be metal hyper- accumulators or are native to soils naturally high in heavy metals, such as serpentine soils, and whose roots form mutualist relationships with arbuscular mycorrhizal fungi (AMF). We hypothesize that: it is possible to discover and quantify new ways to remediate asbestos sites in situ using a combination of hyper- accumulating plants and plants native to serpentine soils coupled with their associated arbuscular mycorrhizal fungi (AMF). We propose to test this hypothesis using three specific strategies: 1) Determine new ways to remediate asbestos piles using iron hyper-accumulating plants, plants native to serpentine soils with AMF associations, and the exudates and metabolites fundamentally responsible for the chemical and physical alteration, 2) Validate the effect, rate and chemical mechanisms of asbestos fiber remediation by chemical analysis and spectroscopy techniques and to produce remediated fibers in suspension to apply to cells in Project 4, and to test directly, in animal model systems, whether remediation of asbestos abrogates its carcinogenic potential in vivo in Project 5, and to determine the size reduction and surface charge change of remediated fibers, which applies to Projects 2 and 3). We will etermine whether soil microbial constituents at the Ambler Superfund site and the relative abundance of different AMF species in greenhouse treatments respond to the presence of asbestos, providing clues to effective agents for bioremediation. Highly controlled greenhouse experiments coupled with Scanning Transmission Electron Microscopy, X-ray Diffraction characterization and Inductively Coupled Plasma Optical Emission Spectrometry will document the efficacy of different plant species and combinations of mycorrhizal fungal species in removing Fe from asbestos and destroying the fibrous structure. Where asbestos is altered at the greatest rates, high throughput DNA sequencing and pyrosequencing will be used to quantity the relative abundance of the different AMF species. The same technique will be used to determine how the AMF community at the Ambler superfund site responds to local concentration of asbestos. This information from the site will inform the greenhouse experiments. We believe that the proposed research will produce new remediation strategies for asbestos at Superfund and Brownfields sites, and will eventually lead to marketing such a technique for other sites of asbestos contamination. If clear remediation results in this trial, a larger translation of the results will be pursued through an application for an NIH Small Business Grant. Our results have direct impact on Project 2 and we will communicate how our asbestos remediation affects asbestos fiber size, transport and aggregate formation. We will work closely to confirm reduced toxicity of remediated fibers with the animal model studies in Project 4, and we will be to take advantage of the in vitro asbestos-induced cell injury models developed in Project 5 to compare the activity of untreated and remediated asbestos fibers. We will also interact significantly with the Administration, Biostatistics and Translation Cores.
This project takes a novel approach to the remediation of asbestos-polluted soil by using biological organisms. We evaluate the efficacy of plants and their associated mycorrhizal (root) fungi in harvesting Fe atoms from asbestos particles and changing the structure of the fibers, which renders them less toxic. The project targets plant species that are either metal hyper-accumulators, known to take up metals in large quantities, or are native to soils naturally high in heavy metals and whose roots form mutually beneficial relationships with mycorrhizal fungi.
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