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
In the progress of the research project "Novel Approaches to Studying the in situ Bioremediation of Complex Mixtures," activities mostly focused on in situ microcosm array (ISMA) design modifications, the mass spectrometric analysis of microbial biomass using proteomics, characterization of microbe-contaminant interactions, the mathematical and procedural methodology of performing mass balances on engineered environments, the study of contaminant mixtures in aquatic and terrestrial environments and completing logistical groundwork for the field studies.
Work continued on the peptide mass fingerprinting approach originally developed by the team for S. wittichii RW1, demonstrating that the technique is powerful when assaying microbial monocultures. The experiments also demonstrated that this method does not perform well when assaying microbial mixed cultures. Therefore, they have initiated the use of MALDI-TOF/TOF mass spectrometry for the determination of catabolic enzymes in whole cell extracts of microbial mono- and mixed cultures. Preliminary results that have been obtained so far are very encouraging and demonstrated the superiority of this approach over peptide mass fingerprinting. Researchers also continued the investigation and characterization of the soluble proteome of the dioxin-degrading bacterium, Sphingomonas wittichii Strain RW1. The whole genome sequence for S. wittichii was obtained in collaboration with the Department of Energy Joint Genome Institute, and an annotation of the organism has been published online on the JGI website.
Studies on the influence of individual components of contaminant mixtures led to the identification of the antimicrobial compounds triclosan and triclocarban as important co-contaminants. Information collected on the environmental occurrence, biodegradability and bioaccumulation of these substances was included in a number of publications. These data also were presented at invited invitations at the National Academies and the headquarters of the Food and Drug Administration and the U.S. EPA in Washington, DC.
Field tests of the ISMA were conducted at the Lawrence Livermore National Laboratory Superfund location DOE Site 300 near Livermore California. Additional tests are planned for the year 2010.
With funding from three supplements to the parent grant, researchers also are pursuing:
- the detection of metabolites of triclocarban in environmental samples,
- an assessment of triclocarban exposures in newborns and adults, and
- the development of a nutrient injection module for use with the in situ microcosm array.