title: Quorum-sensing-directed protein expression in Serratia proteamaculans B5a.
abstract: N-Acyl-L-homoserine-lactone-producing Serratia species are frequently encountered in spoiling foods of vegetable and protein origin. The role of quorum sensing in the food spoiling properties of these bacteria is currently being investigated. A set of luxR luxI homologous genes encoding a putative quorum sensor was identified in the N-(3-oxo-hexanoyl)-L-homoserine lactone (3-oxo-C6-HSL)-producing Serratia proteamaculans strain B5a. The 3-oxo-C6-HSL synthase SprI showed 79 % similarity with EsaI from Pantoea stewartii and the putative regulatory protein SprR was 86 % similar to the SpnR of Serratia marcescens. Proteome analysis suggested that the presence of at least 39 intracellular proteins was affected by the 3-oxo-C6-HSL-based quorum sensing system. The lipB-encoded secretion system was identified as one target gene of the quorum sensing system. LipB was required for the production of extracellular lipolytic and proteolytic activities, thus rendering the production of food-deterioration-relevant exoenzymes indirectly under the control of quorum sensing. Strain B5a caused quorum-sensing-controlled spoilage of milk. Furthermore, chitinolytic activity was controlled by quorum sensing. This control appeared to be direct and not mediated via LipB. The data presented here demonstrate that quorum-sensing-controlled exoenzymic activities affect food quality.
authors.affiliation: Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark.
authors.forename: Allan B
authors.initials: AB
authors.lastname: Christensen
authors.affiliation: Lehrstuhl für Mikrobiologie, Technische Universität München, Am Hochanger 4, D-85350 Freising, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Riedel
authors.affiliation: Lehrstuhl für Mikrobiologie, Technische Universität München, Am Hochanger 4, D-85350 Freising, Germany.
authors.forename: Leo
authors.initials: L
authors.lastname: Eberl
authors.affiliation: Danish Institute for Fisheries Research, Department of Seafood Research, Building 221, c/o Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark.
authors.forename: Lars R
authors.initials: LR
authors.lastname: Flodgaard
authors.affiliation: Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark.
authors.forename: Søren
authors.initials: S
authors.lastname: Molin
authors.affiliation: Danish Institute for Fisheries Research, Department of Seafood Research, Building 221, c/o Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark.
authors.forename: Lone
authors.initials: L
authors.lastname: Gram
authors.affiliation: Section of Molecular Microbiology, BioCentrum-DTU, Building 301, Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark.
authors.forename: Michael
authors.initials: M
authors.lastname: Givskov
mesh_terms: D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002417:Cattle; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D015964:Gene Expression Regulation, Bacterial; D008892:Milk / Q000382:microbiology; D008969:Molecular Sequence Data; D009154:Mutation; D012474:Salmon / Q000382:microbiology; D017422:Sequence Analysis, DNA; D012705:Serratia / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; C088618:lipase activator protein, Bacteria; C088386:homoserine lactone; D015107:4-Butyrolactone