Grantee Research Project Results
Biodegradation of Perfluorinated Compounds
EPA Grant Number: FP917282Title: Biodegradation of Perfluorinated Compounds
Investigators: Tseng, Nancy S
Institution: University of California - Los Angeles , Antioch University - Los Angeles Branch
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2011 through August 31, 2014
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2011) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Pesticides and Toxic Substances
Objective:
Perfluorinated compounds (PFCs) are a group of man-made, emerging contaminants that contain multiple carbon-fluorine (C-F) bonds, making PFCs highly stable and useful in commercial products such as aqueous fire-fighting foams (AFFFs), non-stick coatings, stain-resistant textiles, insulation, sealants and surfactants. These compounds have been found globally and are known carcinogens, reproductive and developmental toxins, and endocrine disrupters. This research project will investigate the biodegradation of PFCs, particularly perfluorooctanoic acid (PFOA) and perfluorooctanoic sulfonate (PFOS), to non-toxic forms by: (1) identifying the degradation capabilities of bacteria and fungi, (2) determining key enzymes involved in the biodegradation pathway, and (3) examining the effects of co-contaminants and environmental conditions.
Approach:
This study will test the hypothesis that microorganisms capable of degrading halogenated compounds also can degrade PFCs. The first objective of this project will be to test the ability of (1) pure cultures of bacteria and fungi and (2) environmental microorganisms from PFC-contaminated sites to breakdown PFCs and fluoroaliphatic compounds. Environmental microorganisms may have acclimated to PFCs and can subsequently degrade PFOA and PFOS. The concentrations of PFCs and fluoroaliphatic compounds will be measured by liquid chromatography tandem mass spectrometry (LC/MS/ MS), and a fluoride ion selective electrode will be used to measure the concentration of fluoride. In addition, biomass changes will be evaluated to determine whether any microorganism can use PFCs as an electron donor or electron acceptor. For those cultures that successfully degrade PFCs, the expression of biodegradative enzymes will be assayed and quantified using reverse-transcriptase quantitative PCR. The degradation products, determined by LC/MS/MS, will be used to propose a biodegradation pathway. Subsequently, the effects of environmental conditions and potential co-contaminants will be explored through the use of batch and flow-through column tests and through the use of experiments utilizing a range of co-contaminant concentrations.
Expected Results:
The biodegradation of PFOA and PFOS is viable because (a) reductive defluorination is thermodynamically favorable and (b) peroxidase mechanisms have been shown to degrade other difficult compounds (e.g., lignin, pesticides, explosives and dyes). This study wants to prove that the biodegradation of PFCs can be mediated by microbes that are either known for degrading halogenated compounds or have been exposed to PFCs for long periods. Once the degradation of PFCs is confirmed, the enzymes utilized by those microorganism(s), the biodegradation rates and the metabolic pathways will be determined. This study also will characterize the effects of environmental conditions and co-contaminants on the biodegradation of PFCs because these influence the mobility and bioavailability of PFCs in addition to the composition and function of microbial communities.
Potential to Further Environmental/ Human Health Protection
The overarching goal of this research is to protect the environment and human health. Physical or chemical degradation technologies may be successful in the laboratory or in off-site reactors, but they can produce PFC-contaminated wastes, are expensive and require long-term pump-andtreat operations. In contrast, bioremediation techniques are easily utilized in situ and can drastically reduce PFCs in the environment without contaminated waste. This approach will prevent future risks from PFCs to humans, fisheries, wildlife and plants.