Survival of Escherichia coli O157 : H7 and Salmonella typhimurium in cow manure and cow manure slurry

An exponential linear destruction was observed for Escherichia coil O157:H7 and Salmonella typhimurium in cattle manure and manure slurry stored at 4, 20 or 37 degrees C. The resulting decimal reduction times ranged From 6 da ys to 3 weeks in manure and from 2 days to 5 weeks in manure slurry. The ma in effects of time as well as temperature were pronounced with the most rap id destruction at 37 degrees C. The ammonia concentration in manure increas ed slightly during storage but did not exceed 0.1%. pH values in the deeper layers of manure remained constant except at 37 degrees C when the pH incr eased by I unit in 60 days. In the surface layers of manure, pH increased b y 1.5-2 units, the oxidation-reduction potential of the manure declined rap idly to values below -200 mV. These changes do not seem to be reflected in changing rates of bacterial destruction. The observed order of destruction makes it possible to predict storage conditions (temperature and time) that will lead to a predetermined level of reduction of the two pathogens. (C) 1999 Federation of European Microbiological Societies. Published by Elsevie r Science B.V. All rights reserved.