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The alternative sigma factor σL of L. monocytogenes promotes growth under diverse environmental stresses


Raimann, Eveline. The alternative sigma factor σL of L. monocytogenes promotes growth under diverse environmental stresses. 2009, University of Zurich, Vetsuisse Faculty.

Abstract

Listeria monocytogenes are important food-borne pathogens that can cause outbreaks of serious human disease. These organisms frequently colonize and proliferate on preserved food products despite exposure to stress conditions induced by low storage temperatures, inclusion of organic acid based preservatives and high osmolarity. To assess alternative sigma factor σL contributions to such stress resistance of L.monocytogenes, quantitative RT-PCR assays and sigL gene deletion mutagenesis were applied in L. monocytogenes EGDe. Transcription of sigL was significantly induced by growth of EGDe under cold, organic acid and elevated NaCl salt concentration stress conditions. The growth of a ΔsigL strain exposed to these stress conditions was also found to be significantly impaired in comparison to that of its isogenic wild-type strain. The contribution of σL to transcription control of cold and NaCl stress adaptation genes, oppA, cspD and clpP was also comparatively assessed in ΔsigL and wild type EGDe cells. Transcription of the oppA gene, which encodes the OppA protein that also promotes L. monocytogenes cold growth, was significantly reduced in cold stress grown ΔsigL cells compared to levels of the wild type EGDe strain.
These findings therefore suggest important roles of σL regulatory pathways in facilitating resistance of L. monocytogenes organisms against stress conditions associated with low storage temperatures, exposure to organic acid and elevated NaCl salt concentrations.

Listeria monocytogenes are important food-borne pathogens that can cause outbreaks of serious human disease. These organisms frequently colonize and proliferate on preserved food products despite exposure to stress conditions induced by low storage temperatures, inclusion of organic acid based preservatives and high osmolarity. To assess alternative sigma factor σL contributions to such stress resistance of L.monocytogenes, quantitative RT-PCR assays and sigL gene deletion mutagenesis were applied in L. monocytogenes EGDe. Transcription of sigL was significantly induced by growth of EGDe under cold, organic acid and elevated NaCl salt concentration stress conditions. The growth of a ΔsigL strain exposed to these stress conditions was also found to be significantly impaired in comparison to that of its isogenic wild-type strain. The contribution of σL to transcription control of cold and NaCl stress adaptation genes, oppA, cspD and clpP was also comparatively assessed in ΔsigL and wild type EGDe cells. Transcription of the oppA gene, which encodes the OppA protein that also promotes L. monocytogenes cold growth, was significantly reduced in cold stress grown ΔsigL cells compared to levels of the wild type EGDe strain.
These findings therefore suggest important roles of σL regulatory pathways in facilitating resistance of L. monocytogenes organisms against stress conditions associated with low storage temperatures, exposure to organic acid and elevated NaCl salt concentrations.

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Additional indexing

Item Type:Dissertation
Referees:Stephan R, Loessner M J
Communities & Collections:05 Vetsuisse Faculty > Institute of Food Safety and Hygiene
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
Language:English
Date:2009
Deposited On:13 Jan 2010 14:59
Last Modified:05 Apr 2016 13:38
Related URLs:http://opac.nebis.ch/F/?local_base=EBI01&con_lng=GER&func=find-b&find_code=090&request=001826266
Permanent URL: http://doi.org/10.5167/uzh-25709

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