Effects of water activity, ammonia and Corynebacterium urealyticum on the survival of Salmonella Typhimurium in sterile poultry litter.

Aims: This study examined the effects of water activity (a ), ammonia and Corynebacterium urealyticum on the survival of Salmonella Typhimurium in sterile poultry litter.

Methods And Results: Sterile poultry litter inoculated with S. Typhimurium was adjusted to pH 9.0, various a levels (0.84, 0.92 and 0.96), and total ammonia nitrogen levels were increased either by the addition of ammonium sulphate or C. urealyticum inoculation with 1% urea added. All litter treatments were incubated at 30°C and sampled daily for five days. Similar results were observed at each a level in both experiments. At 0.84 and 0.92 a , S. Typhimurium populations in litter fell below 1 log CFU g within 5 days, with no significant differences between the controls and increased ammonia treatments. At 0.96 a , Salmonella populations treated with increased ammonia levels were significantly lower than control treatments on days 1-5.

Conclusions: This study showed that C. urealyticum can produce ammonia in litter at higher a levels with sufficient available urea and that the antimicrobial efficacy of ammonia is dependent on high a (~0.96) in litter.

Significance And Impact Of The Study: These results provide insights into the production of ammonia in litter, its antimicrobial efficacy in litter and the importance of a in this interaction.