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Imprint
Microbial stress response of Campylobacter jejuni and its role in food processing
Project
Project code: BfR-BIOS-08-1322-221
Contract period: 01.02.2007
- 31.12.2009
Purpose of research: Applied research
To decrease foodborne human Campylobacter infections, apart from the reduction of the Campylobacter contamination domestic animal and the avoidance of cross contamination, the reduction of the pathogen within the food chain by technological processes plays a crucial role.
Despite its high sensitivity against stressors and its ? in opposite of other bacteria - small equipment with genes, which encode factors for the stress response, Campylobacter spp. are able to survive in the environment and within the food chain.
A goal of the work was to describe - exemplary at selected technological stressors - the survival of Campylobacter jejuni/coli in different growth phases under the influence of such stressors.
In addition, extensive temperature-time-matrices were provided. It could be observed, that Campylobacter exhibits a typical stationary phase stress response with higher resistance to heat stress under tested conditions.
Although the entrance into the stationary phase of Campylobacter jejuni is not regulated by rpoS (a RpoS homologous is missing), other regulatory systems take over (like CsrA/CsrB, carbon storage modulator) and control the expression of stationary-phase-induced genes.
Accompanying gene expression analyses demonstrate the rapid activation of the heat shock response at the expression level. Already after short heat shocks at 48° C RNA degradation processes were observed, which result substantial losses of the bacterial count.
To decrease foodborne human Campylobacter infections, apart from the reduction of the Campylobacter contamination domestic animal and the avoidance of cross contamination, the reduction of the pathogen within the food chain by technological processes plays a crucial role.
Despite its high sensitivity against stressors and its ? in opposite of other bacteria - small equipment with genes, which encode factors for the stress response, Campylobacter spp. are able to survive in the environment and within the food chain.
A goal of the work was to describe - exemplary at selected technological stressors - the survival of Campylobacter jejuni/coli in different growth phases under the influence of such stressors.
In addition, extensive temperature-time-matrices were provided. It could be ob-served, that Campylobacter exhibits a typical stationary phase stress response with higher resistance to heat stress under tested conditions.
Although the entrance into the stationary phase of Campylobacter jejuni is not regulated by rpoS (a RpoS homologous is missing), other regulatory systems take over (like CsrA/CsrB, carbon storage modulator) and control the expression of stationary-phase-induced genes.
Accompanying gene expression analyses demonstrate the rapid activation of the heat shock response at the expression level. Already after short heat shocks at 48° C RNA degradation processes were observed, which result substantial losses of the bacterial count.
The ability to adapt swiftly to changing environmental conditions characterizes the survival ability of single bacterial species or individual strains.
Goal of this study was to describe the heat shock response of C. jejuni encountering mild temperature increases. Mild stressors might act as stimulator of adaptation mechanisms.
By using complete genome microarray analysis we were able to describe the heat shock response of C. jejuni NCTC 11168 in detail.
Campylobacter spp. lack of some typical stress response mechanisms known from other gram negative bacteria which are necessary for survival after different stresses. To get more insight into the Campylobacter stress response on protein level the method of 2D-Gelelectrophoreses has been established and expression of total protein after heat or acid stress was analysed. An increased expression level of some chaperons was detected after heat induced stress. As protein expression level of these proteins kept stable after acid stress the response to the two stressors heat and acid seems to be regulated differently.
Section overview
Subjects
- Food Processing
- Food microbiology
