Superfund Research Program
Novel Approaches to Studying the in situ Bioremediation of Complex Mixtures
Project Leader: Rolf Ulrich Halden
Grant Number: R01ES015445
Funding Period: 2006-2009
Year: 2010 2009
Superfund sites across the U.S contain mixtures of pollutants that contaminate underlying aquifers. The environmental fate of these contaminants, and human exposures to them, are still ill defined. Whereas single pollutant/microorganism interactions can be determined easily in the lab, no satisfactory tools exist for predicting the fate and effect of mixtures in the environment. Dr. Halden's research group developed novel tools and methodologies for determining the occurrence and treatability of contaminant mixtures as well as their associated human body burdens and health effects. The work produced a novel remedial design tool, the in situ microcosm array (ISMA), that enables one to screen multiple treatment technologies for their effectiveness in removing contaminant mixtures from groundwater in situ. The ISMA is a field-deployable, self-contained miniaturized laboratory allowing for parallel in situ testing. Upon deployment, incubation, and retrieval from a groundwater well, the ISMA is analyzed to reveal the impact of mixture components on the rates of pollutant degradation and on the structure and function of microbial communities. Using computer-aided design (CAD) and rapid prototyping, the researchers developed ISMA devices and evaluated their performance at Superfund and other hazardous waste sites. The tool, unmatched in its functionality when compared to current technologies, is now being commercialized.
The project also explored the use in bioremediation of Sphingomonas wittichii Strain RW1, a unique bacterium capable of using dioxins as growth substrates. In collaboration with the Joint Genome Institute, the reserach group sequenced the whole genome of this bacterium and characterized its proteome. Microbiological studies of environmental samples taken near a Superfund site in Baltimore, MD, resulted in the identification and cultivation of additional bioremediation agents that are capable of detoxifying organohalogen mixtures. One microbial culture contained never before reported microbes capable of growth on an antimicrobial compound, triclocarban. Tandem mass spectrometric analyses of sediment, sludge, and water as well as cord blood, urine and breast milk, yielded evidence of toxic mixtures in the environment and in exposed human populations. Proteomic analyses yielded the first map of the human cord blood proteome and biomarkers of toxic exposures detectable therein. This research advanced our understanding of the occurrence and management of toxic mixtures.