Survival of Salmonella enterica Typhimurium in water amended with manure

Outbreaks of Salmonella enterica have been associated with water sources. Survival of S. enterica in various environments has been studied but survival in water has rarely been attempted. In two separate experiments, we examined the survival of S. enterica Typhimurium in clean spring water at various eutrophication levels and temperatures. In the first experiment, lasting for 135 days, survival of S. enterica (10¹⁰ CFU/ml) in water with 0, 50, 100, 500, and 1,000 mg/liter of added carbon at 7, 17, and 27°C was monitored weekly. In the second experiment, lasting for 3 weeks, survival of S. enterica in water at 0, 100, and 200 mg/ liter of added carbon and 27°C was studied daily. Each experiment had four replicates. Dissolved organic carbon was measured daily in each experiment. At the beginning, midpoint, and end of the survival study, microbial communities in both experiments were assessed by denaturing gradient gel electrophoresis (DGGE). Even at minimal carbon concentrations, S. enterica survived for at least 63 d. Survival of Salmonella was highly dependent on eutrophication levels (as measured by dissolved organic carbon) and temperature, increasing at high eutrophication levels, but decreasing at high temperatures. Survival was also strongly affected by microbial competition or predation.