7/1/2010 - 6/30/2012
- Shangping Xu, UW-Milwaukee
Recent publications showed that antibiotic resistant bacteria were prevalent in Wisconsin’s dairy manure. Improper manure storage and the application of manure as a fertilizer to agricultural fields can lead to groundwater contamination by antibiotic resistant bacteria. Because 70% of Wisconsin’s population depend on groundwater as the drinking water source, spread of antibiotic resistant bacteria in the groundwater system pose serious public health risks. Our knowledge of the mechanisms and processes that govern the transport of antibiotic resistant bacteria in soil and groundwater, which is essential to the assessment of the associated health risks, is very limited. It was recently observed that tetracycline resistance could significantly enhance the mobility of manure-derived E. coli in saturated porous media. The difference in the mobility of tetracycline resistant and tetracycline susceptible E. coli was related to variations in cell surface properties. It is thus hypothesized that tetracycline resistance will influence the transport of manure-derived E. coli in unsaturated soil. The primary goal of this proposed project is to examine the transport of manure-derived, tetracycline resistant E. coli in partially saturated soil. Particularly, this research will investigate the influence of pore water chemistry and soil moisture content on the retention and remobilization of tetracycline resistant E. coli in unsaturated soil. Findings from this proposed research will advance our understanding of the mechanisms that control the transport of antibiotic resistant bacteria in soil and groundwater, which are essential for the development and validation of predictive mathematical models; and provide a basis for evaluating the public health risks associated with the storage and land application of dairy manure. Potential users of the expected findings include dairy farmers, policy makers at state and local levels and water professionals. This project will also have broader applications by advancing our understanding of the spread of antibiotic resistance in the environment.