Deactivation of Pathogenic Escherichia Coli O157:H7 In Dairy Manure Through Modification of pH and Temperature.

The enteric pathogenic bacteria E. coli O157:H7 is widely present in food animal production farms, and can pose a serious threat to human health if the pathogen moves off-farm and into the food production system.  To extend our previously-reported studies on control of Salmonella enterica serovar Newport in the dairy farm environment, we inoculated E. coli O157:H7 labeled with green fluorescence protein (gfp) into dairy manure and adjusted the pH in the range 4 to 5 with aluminum sulfate or to pH 10 to 12 with hydrated lime, and followed the deactivation kinetics of the pathogen over time through plating on sorbitol-MacConkey differential agar.  Similar to Salmonella, at pH between 4 to 5 and 10 to 11, pathogen concentrations in the manure demonstrated a transient decline by up to 100-fold before increasing again.  E. coli O157:H7 had relatively low survivability in manure; in most treatments it was not found beyond 14 days.  E. coli survival characteristics in manure incubated at 4, 22 or 37 degrees C will be discussed.