title: Contribution of Lactococcus lactis reducing properties to the downregulation of a major virulence regulator in Staphylococcus aureus, the agr system.
abstract: Staphylococcus aureus is a major cause of food poisoning outbreaks associated with dairy products, because of the ingestion of preformed enterotoxins. The biocontrol of S. aureus using lactic acid bacteria (LAB) offers a promising opportunity to fight this pathogen while respecting the product ecosystem. We had previously established the ability of Lactococcus lactis, a lactic acid bacterium widely used in the dairy industry, to downregulate a major staphylococcal virulence regulator, the accessory gene regulator (agr) system, and, as a consequence, agr-controlled enterotoxins. In the present paper, we have shown that the oxygen-independent reducing properties of L. lactis contribute to agr downregulation. Neutralizing lactococcal reduction by adding potassium ferricyanide or maintaining the oxygen pressure constant at 50% released agr downregulation in the presence of L. lactis. This downregulation still occurred in an S. aureus srrA mutant, indicating that the staphylococcal respiratory response regulator SrrAB was not the only component in the signaling pathway. Therefore, this study clearly demonstrates the ability of L. lactis reducing properties to interfere with the expression of S. aureus virulence, thus highlighting this general property of LAB as a lever to control the virulence expression of this major pathogen in a food context and beyond.
authors.affiliation: Université de Toulouse, INSA, UPS, INP, LISBP, Toulouse, France INRA, UMR792, Toulouse, France CNRS, UMR5504, Toulouse, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Nouaille
authors.affiliation: INRA, UMR1253, Rennes, France Agrocampus Ouest, UMR1253, Rennes, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Rault
authors.affiliation: INRA, UMR1253, Rennes, France Agrocampus Ouest, UMR1253, Rennes, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Jeanson
authors.affiliation: Université de Toulouse, INSA, UPS, INP, LISBP, Toulouse, France INRA, UMR792, Toulouse, France CNRS, UMR5504, Toulouse, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Loubière
authors.affiliation: INRA, UMR1253, Rennes, France Agrocampus Ouest, UMR1253, Rennes, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Le Loir
authors.affiliation: INRA, UMR1253, Rennes, France Agrocampus Ouest, UMR1253, Rennes, France sergine.even@rennes.inra.fr.
authors.forename: Sergine
authors.initials: S
authors.lastname: Even
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D013294:Lactococcus lactis / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: C095698:Agr protein, Staphylococcus aureus; D001426:Bacterial Proteins; D015534:Trans-Activators; D010100:Oxygen