Project Director Ashley Bandy: Mobility of stable isotope-labeled Escherichia coli within karst aquifers

The PD will work with mentors Dr. Kim Cook, of the USDA-ARS Animal Waste Management Research Unit, and Dr. Alan Fryar, a hydrogeologist at the University of Kentucky. This predoctoral application for a research-based project fits within the Agriculture and Natural Resources Science for Climate Variability and Change Challenge Area and Renewable energy, Natural resources, and Environment Foundational Program Area and will increase understanding of fundamental aspects of microbial movement in the environment, which has the potential for broad application toward improving food safety and security by decreasing pathogen transport to valuable and often limited water resources, showing relevance to the goals of the Fellowship Grant Program. Effects of global climate change are combining with growing population to strain water resources, generating an urgent need for more research to understand fundamental processes that control pathogen movement. Field data on survival and transport of agricultural isolates of the indicator organism Escherichia coli (E. coli) can be applied to generate adequate transport models and used by regulatory agencies for decision-making processes in regards to safety procedures and best management practices for the prevention of contamination. Currently, bacterial transport and attenuation in karst aquifers are not well understood. Karst areas constitute approximately 15% of the contiguous U.S., and 40% of the terrain east of the Mississippi River. Objectives of the study include 1) evaluate transport of 15N-labelled E. coli within a karst basin compared to fluorescent dye and latex microspheres and 2) examine transport properties of two different isolates of 15N-labelled E. coli through epikarst. Minimal filtration and turbulent flow of water in karst systems can mobilize various particles and spread contaminants, including pathogens. Common tracers such as fluorescent dyes and microspheres do not exhibit the same surface chemistries and transport properties as contaminants, such as microorganisms, as seen in proof-of-concept studies in which bacteria and microspheres are remobilized during storm events after initial injection. Lab-scale studies also suggest that E. coli strain-level phenotype and genotype effect transport. Comparisons will also be made between the transport through well-developed epikarst of two E. coli isolates, which were shown in lab-scale studies to significantly differ in adhesion properties.