title: Oxidation-reduction potential regulates RpoS levels in Salmonella Typhimurium.
abstract: OBJECTIVE
  The aim of this work was to investigate the connection between oxidation-reduction (redox) potential and stationary phase induction of RpoS in Salmonella Typhimurium.
  
  
  RESULTS
  A lux-based reporter was used to evaluate RpoS activity in S. Typhimurium pure cultures. During growth of S. Typhimurium, a drop in the redox potential of the growth medium occurred at the same time as RpoS induction and entry into stationary phase. An artificially induced decrease in redox potential earlier during growth reduced the time to RpoS induction and Salmonella entered the stationary phase prematurely. In contrast, under high redox conditions, Salmonella grew unaffected and entered the stationary growth phase as normal, although RpoS induction did not occur. As a consequence, stationary phase cells grown in the high redox environment were significantly more heat sensitive (P < 0.05) than those grown under normal conditions.
  
  
  CONCLUSIONS
  This work suggests that redox potential can regulate RpoS levels in S. Typhimurium and can thus, control the expression of genes responsible for thermal resistance.
  
  
  CONCLUSIONS
  The ability to manipulate RpoS induction and control stationary phase gene expression can have important implications in food safety. Early RpoS induction under low redox potential conditions can lead to enhanced resistance in low cell concentrations to inimical processes such as heat stress. Inhibition of RpoS induction would abolish stationary phase protective properties making cells more sensitive to common food control measures.
authors.affiliation: School of Biomedical and Molecular Sciences, University of Surrey, Guildford, Surrey, UK.
authors.forename: E
authors.initials: E
authors.lastname: Komitopoulou
authors.forename: N J
authors.initials: NJ
authors.lastname: Bainton
authors.forename: M R
authors.initials: MR
authors.lastname: Adams
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis*; D003470:Culture Media; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics*; D006358:Hot Temperature; D010084:Oxidation-Reduction; D012486:Salmonella typhimurium / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D012808:Sigma Factor / Q000032:analysis*; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria