Survival of Salmonella enteritidis and Salmonella typhimurium in chicken manure at different levels of water activity.

Survival of Salmonella enteritidis and Salmonella typhimurium in chicken manure at different levels of water activity (aw) was determined. The aw was adjusted by means of saturated salts with defined equilibrium relative humidity and the manure samples were stored aerobically at 20 degrees C. At aw levels higher than 0.93, a moderate increase in colony-forming units over 8-9 h was found for both strains; at aw levels of 0.89-0.75, there was a thousand-fold reduction. Extended storage resulted in a million-fold reduction of Salmonella enteritidis in 8 days at an aw of 0.89. At higher and lower levels of aw, the reduction was less extensive.