Survival of Salmonella typhimurium and Escherichia coil O157 : H7 in poultry manure and manure slurry at sublethal temperatures

Exponential inactivation was observed for Salmonella typhimurium and Escher ichia coli O157:H7 in poultry manure with decimal reduction rimes ranging f rom half a day at 37 C to 1-2 wk at 4 C. There was no material difference i n inactivation rates between S. typhimurium and E. coli O157:H7. Inactivati on was slower in slurries made by mixing two parts of water with one part o f manure; decimal reduction times (time required for 90% destruction) range d from 1-2 days at 37 C to 6-22 wk at 4 C. Escherichia coli O157:H7 consist ently exhibited slightly slower inactivation than S. typhimurium. Log decim al reduction time fur both strains was a linear function of storage tempera ture for manure and slurries. Chemical analysis indicated that accumulation of free ammonia in poultry manure was an important factor in inactivation of the pathogens. This finding was experimentally confirmed for S. typhimur ium by adding ammonia directly to peptone water or to bovine manure, which was naturally low in ammonia, and adjusting pH to achieve predetermined lev els of free ammonia.