CHEEC Seed Grants: FY 1995

Expression of toluene dioxygenase under various redox and substrate conditions 
NA Lynch, Department of Preventive Medicine and Environmental Health; PJ Alvarez, Department of Civil and Environmental Engineering, The University of Iowa

Development of exposure databases for nitrate contamination of private drinking water/groundwater supplies 
GR Hallberg, University Hygienic Laboratory, The University of Iowa; KD Rex, Iowa Department of Natural Resources-Geological Survey Bureau

Effect of poplar trees on microbial populations important to hazardous waste bioremediation 
JL Jordahl, LA Licht, PJ Alvarez, Department of Civil and Environmental Engineering, The University of Iowa

The use of an automated PCR/ELISA technique to detect indicators of fecal contamination
LD Sutton, Department of Pathology; GR Hallberg, University Hygienic Laboratory; NA Lynch, Department of Preventive Medicine and Environmental Health, The University of Iowa

 


Expression of toluene dioxygenase under various redox and substrate conditions 
Investigators: NA Lynch, Department of Preventive Medicine and Environmental Health; PJ Alvarez, Department of Civil and Environmental Engineering, The University of Iowa 
Bioremediation, the enhancement of microbial activity to degrade environmental pollutants within aquifers, show great promise to reduce health risks associated with groundwater contamination. The success of bioremediation, however, can be limited by the availability of electron acceptors (e.g. O2) and by the expression of appropriate catabolic enzymes (e.g. toluene dioxygenase). The dissolved oxygen concentration threshold for the expression of toluene dioxygenase, and the ability of various target contaminants and other substrate to induce this enzyme will be investigated. Toluene dioxygenase is an ideal enzyme for a study of bioremediation because of its ability to catalyze the aerobic biotransformation of a wide variety of ubiquitous priority pollutants, including petroleum hydrocarbons (e.g. benzene, toluene, and xylenes) and solvents (e.g. trichlorethylene). Enzyme expression will be quantified using an enzyme linked immuno sorbent assay (ELISA). This project will enhance understanding of the limitations of catabolic enzyme expression during bioremediation. The identification of non-polluting enzyme inducers could also lead to improved bioremediation of trace pollutants and to the development of better cometabolic processes.

Development of an exposure database for nitrate contamination of private drinking-water/groundwater supplies 
Investigators: GR Hallberg, University Hygienic Laboratory; KD Rex, Iowa Department of Natural Resources, Geological Survey Bureau, The University of Iowa 
Nitrate is the most common chemical contaminant in groundwater and drinking water in Iowa. This study will provide a cost-effective method for surveillance of nitrate contamination of private drinking-water supplies that can be used for exposure assessment, epidemiological studies, and monitoring of nitrate contamination over time. The University Hygienic Laboratory database of private well-water analyses (approximately 10,000 nitrate analyses/year) will be related to the Iowa Groundwater Vulnerability Regions (GVR) using the IDNR Geographic Information System. Zip-code areas will be spatially related to the GVR units and then the UHL water-quality data will be summarized by zip-codes, by GVR unit, by well depth, and by year. This will provide a sensitive analytical tool to assess spatial and temporal differences in water quality. It is proposed that this approach be used to develop an annual report of water-quality trends in Iowa, summarizing exposure and resource implications.

Effect of poplar trees on microbial populations important to hazardous waste bioremediation 
Investigators: JL Jordahl, LA Licht, PJ Alvarez, Department of Civil and Environmental Engineering, The University of Iowa
Phytoremediation, the use of plants to remove pollutants from the environment, holds great promise to reduce health risks associated with groundwater and soil contamination. It is widely recognized as an under utilized technology, and its successful application on a large scale will require continued input from basic research. Poplar trees could enhance site remediation via contaminant uptake and in-plant degradation, by minimizing off-site migration, or by enhancing microbial degradation in the rhizosphere. This project will characterize the microbial community beneath 7-year-old poplar trees. The hypothesis is that poplar roots exert selective pressure for the proliferation of microorganisms important to bioremediation. These include microorganisms capable of removing nitrate by denitrification, as well as microorganisms that can degrade carcinogens such as benzene or atrazine. Most Probable Number (MPN) techniques will be used to characterize and enumerate indigenous microorganisms with such specific traits. Viable plate techniques will be used to assess microbial diversity. Predominant microbial colonies will be isolated and identified using a BIOLOG system. Background soil will also be characterized to serve as a control for the root effect. Such information will contribute to the rational development of phytoremediation.

Publication:  Jordahl JL, Foster L, Schnoor JL, Alvarez PJ; Effect of Poplar Trees (Populus spp.) on Microbial Populations Important to Hazardous Waste Bioremediation. Environ Toxicol Chem. 1997; 16(6):1318-1321

The use of automated PCR/ELISA technique to detect indicators of fecal contamination 
Investigators: L Sutton, Department of Pathology; GR Hallberg, University Hygienic Laboratory; NA Lynch, Department of Preventive Medicine and Environmental Health, The University of Iowa 
Fecal contamination of water supplies is a major cause of infectious disease with consequences ranging from minor illness to patient death. Current culture-based detection methods are decades old and take days to complete. Once identified, the presence of specific pathogens can take additional time. Clearly, the development of modern methods of detection are imperative. Automated polymerase chain reaction (PCR)-based methods would have major advantages over current procedures. The automation (1) minimizes risks of amplicon contamination and (2) allows for reliable, high throughput analysis. The PCR methodology (1) allows rapid turnaround time of hours instead of days, (2) permits adjustable sensitivity and specificity, (3) enables rapid subsequent analysis of positives samples to identify specific pathogens, and (4) identifies hard to culture pathogens. Such a system would help to minimize exposure to contaminated water sources and, when exposure has occurred, to rapidly guide appropriate antimicrobial chemotherapy, thus reducing morbidity and mortality.