title: A five-gene stress survival islet (SSI-1) that contributes to the growth of Listeria monocytogenes in suboptimal conditions.
abstract: OBJECTIVE
  The aim of this study was to examine the contribution of a five-gene islet (lmo0444 - lmo0448) to the growth of Listeria monocytogenes under suboptimal conditions.
  
  
  RESULTS
  Bioinformatics and PCR analyses revealed that a five-gene islet is present in c. half of all L. monocytogenes strains examined (66 in total). A deletion mutant that lacks the entire c. 8·7-kb islet was created in L. monocytogenes strain LO28. This mutant was impaired in growth at low pH and at high salt concentrations and demonstrated a decreased ability to survive and grow in a model food system (frankfurters). Transcriptional analysis revealed that the islet is self-regulated in that the product of lmo0445 regulates the expression of the other four genes. A role of the alternative stress sigma factor SigB in regulating the islet was also uncovered.
  
  
  CONCLUSIONS
  The five-gene islet (herein designated as SSI-1; stress survival islet 1) contributes to the growth of L. monocytogenes under suboptimal conditions.
  
  
  CONCLUSIONS
  SSI-1 may contribute to the survival of certain strains of L. monocytogenes in food environments.
authors.affiliation: Department of Microbiology, University College Cork, Cork, Ireland.
authors.forename: S
authors.initials: S
authors.lastname: Ryan
authors.forename: M
authors.initials: M
authors.lastname: Begley
authors.forename: C
authors.initials: C
authors.lastname: Hill
authors.forename: C G M
authors.initials: CG
authors.lastname: Gahan
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004777:Environment; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008089:Listeria monocytogenes / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D008461:Meat Products / Q000382:microbiology; D010454:Peptide Termination Factors / Q000378:metabolism; D012808:Sigma Factor / Q000378:metabolism; D013312:Stress, Physiological / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D010454:Peptide Termination Factors; C545356:PrfA protein, Listeria monocytogenes; C079011:SigB protein, Bacteria; D012808:Sigma Factor