TY - JOUR
T1 - Influence of temperature and predation on survival of Salmonella enterica serovar Typhimurium and expression of invA in soil and manure-amended soil
AU - García, R.
AU - Bælum, J.
AU - Fredslund, L.
AU - Santorum, P.
AU - Jacobsen, C.S.
PY - 2010/8/1
Y1 - 2010/8/1
N2 - The effects of three temperatures (5, 15, and 25°C) on the survival of Salmonella enterica serovar Typhimurium in topsoil were investigated in small microcosms by three different techniques: plate counting, invA gene quantification, and invA mRNA quantification. Differences in survival were related to the effect of protozoan predation. Tetracycline-resistant Salmonella serovar Typhimurium was inoculated into soil and manure-amended soil at 1.5 × 108 cells g soil−1.
Population densities were determined by plate counting and by molecular
methods and monitored for 42 days. Simultaneous extraction of RNA and
DNA, followed by quantitative PCR, was used to investigate invA gene levels and expression. Analysis by these three techniques showed that Salmonella
serovar Typhimurium survived better at 5°C. Comparing DNA and CFU
levels, significantly higher values were determined by DNA-based
techniques. invA mRNA levels showed a fast decrease in activity,
with no detectable mRNA after an incubation period of less than 4 days
in any of the soil scenarios. A negative correlation was found between Salmonella
serovar Typhimurium CFU levels and protozoan most probable numbers, and
we propose the role of the predator-prey interaction as a factor to
explain the die-off of the introduced strain by both culture- and DNA
quantification-based methods. The results indicate that temperature,
manure, and protozoan predation are important factors influencing the
survival of Salmonella serovar Typhimurium in soil.
AB - The effects of three temperatures (5, 15, and 25°C) on the survival of Salmonella enterica serovar Typhimurium in topsoil were investigated in small microcosms by three different techniques: plate counting, invA gene quantification, and invA mRNA quantification. Differences in survival were related to the effect of protozoan predation. Tetracycline-resistant Salmonella serovar Typhimurium was inoculated into soil and manure-amended soil at 1.5 × 108 cells g soil−1.
Population densities were determined by plate counting and by molecular
methods and monitored for 42 days. Simultaneous extraction of RNA and
DNA, followed by quantitative PCR, was used to investigate invA gene levels and expression. Analysis by these three techniques showed that Salmonella
serovar Typhimurium survived better at 5°C. Comparing DNA and CFU
levels, significantly higher values were determined by DNA-based
techniques. invA mRNA levels showed a fast decrease in activity,
with no detectable mRNA after an incubation period of less than 4 days
in any of the soil scenarios. A negative correlation was found between Salmonella
serovar Typhimurium CFU levels and protozoan most probable numbers, and
we propose the role of the predator-prey interaction as a factor to
explain the die-off of the introduced strain by both culture- and DNA
quantification-based methods. The results indicate that temperature,
manure, and protozoan predation are important factors influencing the
survival of Salmonella serovar Typhimurium in soil.
UR - http://www.scopus.com/inward/record.url?scp=77955577106&partnerID=8YFLogxK
U2 - 10.1128/AEM.00628-10
DO - 10.1128/AEM.00628-10
M3 - Article
VL - 76
SP - 5025
EP - 5031
JO - Applied and Environmental Microbiology
JF - Applied and Environmental Microbiology
SN - 0099-2240
IS - 15
ER -