2008 Annual Report
1a.Objectives (from AD-416)
Our overall goals are 1. to understand better the survival kinetics and hydrologic transport characteristics of manure pathogens and their associated fecal indicator bacteria in agricultural watersheds, and 2. to improve our understanding of the emissions of ammonia and greenhouse gases from manures and manure applications. To accomplish goal 1., we propose three interrelated objectives: A) develop a method detection limit for Salmonella in environmental soil, poultry litter, and water samples with quantitative, real-time polymerase chain reaction (qPCR); B) determine inactivation or die off rates of Salmonella and the fecal indicator bacteria Escherichia coli and fecal Enterococcus spp. In field soils under controlled and field conditions; and C: determine the hydrologic transport characteristics of manure pathogens and fecal indicator bacteria at the field plot and small zero-order watershed scales. To accomplish goal 2., we propose to pursue the following two objectives: D) to measure ammonia and global-change trace gas emissions from land application of poultry litter under different tillage management, and E) from wetlands receiving nitrogen inputs from pastures.
1b.Approach (from AD-416)
Goal 1.: A real-time, quantitative polymerase chain reaction (qPCR) method will be developed to quantity the concentrations of Salmonella in poultry litter, and in environmental soil and water samples exposed to field applied poultry litter. With sentinel chambers, the aforementioned qPCR method, and defined cultural methods inactivation rates of Salmonella, and fecal indicator bacteria in agricultural soils will be determined under laboratory and field conditions. In collaboration with the Poultry Microbiological Safety Unit at the Russell Research Center, Athens,GA, and Southeast Watershed Research Laboratory, Tifton, GA overland transport of manure pathogens and fecal indicator bacteria from field applied poultry litter will be characterized at the field-plot level under various slope and aspect and under conditions of simulated rain, and at the small watershed-scale level that will depend on natural weather conditions. Goal 2.: Soil chambers will be used to measure gaseous emissions from poultry litter after soil application. Emissions will be evaluated under different tillage management systems. Small riparian/wetland areas will be studied to determine the proportion of hydrologic input nitrogen is transformed into gaseous nitrogenous emissions.
This project contributes to the Manure and Byproduct Utilization National Program (206) Action Plan Area 3.C. Pathogens and Pharmaceutically Active Compounds (PACs) Component, Focus Area 1. Methods Assessment and Development, Focus Area 2. Fate and Transport of Pathogens, and Problem Area 2A. Inactivation Rates and Transport Characteristics of Pathogens from Animal Agriculture. A new method that combines culture-based most probable number methodology with a real-time PCR confirmation step for enumerating Salmonella and E. coli 0157:H7 in environmental water and soil samples has been developed and supersedes the non-culture-based real-time, quantitative PCR method that was originally proposed for this project. With this new method a limit of detection for Salmonella and E. coli 0157:H7 in environmental water and soil samples has been established. With this new method of enumerating pathogens combined with sentinel chamber technology experiments comparing die-off rates of the pathogen E. coli 0157:H7 and generic fecal indicator bacteria, E. coli and fecal enterococci have been undertaken. In anticipation of rain events with runoff, loads of fecal of indicator bacteria have been determined for the four cropped and instrumented watersheds that receive poultry litter and periodic cattle grazing.
Rain Simulation Experiments Demonstrated that Applications of Poultry Litter at Appropriate Agronomic Rates Appear to Have Little Potential of Contaminating Surface Waters with Pathogens, Hormones or Antibiotics. Because poultry litter contains fecal bacteria, sex hormones, and low levels of antibiotics it is important to determine if poultry litter poses a risk to public health. Controlled rainfall simulations on long-term no-till and conventional tillage fields with poultry litter applications at rates recommended for crop production did not contribute to the loads of fecal bacteria, hormones, or antibiotics in runoff to surface waters. Rainfall following application of poultry litter at recommended agronomic levels, and depending on the concentrations of fecal bacteria and hormones, appears to have little potential of contaminating surface waters with pathogens or hormones. This is important information for the poultry industry and environmental protection agencies since surface waters contaminated with pathogens or hormones from poultry litter are likely an indication of inappropriate or mismanagement of litter applications. This accomplishment contributes to the Manure and Byproduct Utilization National Program (206) Action Plan Area 3.C. Pathogens and Pharmaceutically Active Compounds (PACs) Component, Focus Area 2. Fate and Transport of pathogens, and Focus Area 3. Pharmaceutically Active Compounds.
Method Developed for Determining Dilute Concentrations of Escherichia coli 0157:H7 in Surface Waters. Watersheds with animal agriculture have the potential to adversely impact recreational waters and threaten public health by contaminating surface waters with fecal pathogens such as E. coli 0157:H7. To understand and manage the fate and transport of E. coli 0157:H7 in agricultural watersheds a combination of a filtration method, culture-based a most probable number (MPN) method and a real-time polymerase chain reaction (PCR) confirmation method for enumerating dilute densities of E. coli 0157:H7 in environmental waters was developed. This method has determined the density of E. coli 0157:H7 in 20-liter samples taken from the inflow and outflow streams of a pond in an agricultural watershed as low as 0.1 Salmonella cells/liter and identified substantial fluxes of E. coli 0157:H7 when the fecal indicator bacterium E. coli was not detected. The sensitivity of this method will improve our understanding of the fate and transport of E. coli 0157:H7 in agricultural watersheds, enhance our ability to assess this pathogen’s risk to public health, and it will prove helpful in identifying the actual sources of this pathogen because this method offers the potential for developing culture collections of E. coli 0157:H7. This accomplishment contributes to the Manure and Byproduct Utilization National Program (206) Action Plan Area 3.C. Pathogens and Pharmaceutically Active Compounds (PACs) Component, Focus Area 1. Methods Assessment and Development, and Focus Area 2. Fate and Transport of pathogens.
5.Significant Activities that Support Special Target Populations
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|Number of Non-Peer Reviewed Presentations and Proceedings||1|
|Number of Newspaper Articles and Other Presentations for Non-Science Audiences||1|
Jenkins, M., Endale, D.M., Fisher, D.S., Gay, P.A. 2009. Most probable number methodology for quantifying dilute concentrations and fluxes of Escherichia coli O157:H7 in surface waters. Journal of Applied Microbiology. 106:572-579.
Jenkins, M., Truman, C.C., Siragusa, G.R., Line, J.E., Bailey, J.S., Frye, J.G., Endale, D.M., Franklin, D.H., Schomberg, H.H., Fisher, D.S., Sharpe, R.R. 2008. Rainfall and tillage effects on transport of fecal bacteria and sex hormones 17ß-estradiol and testosterone from broiler litter applications to a Georgia Piedmont Ultisol. Science of the Total Environment. 403(1-3):154-163.