title: The quorum sensing luxS gene is induced in Lactobacillus acidophilus NCFM in response to Listeria monocytogenes.
abstract: The luxS gene involved in quorum sensing has been shown to control different behaviour of probiotic lactobacilli. In this study we investigated if luxS in Lactobacillus acidophilus NCFM was up-regulated in response to Listeria monocytogenes EGD-e. The two bacterial strains were grown in mono- and co-culture and the growth of both bacteria and the transcriptional level of luxS in L. acidophilus cells were monitored. Contrary to L. acidophilus, the growth of L. monocytogenes was significantly affected by co-cultivation. Transcriptional analysis showed that the expression of luxS increased during exponential growth in L. acidophilus cells with the highest level in the late-exponential growth phase, decreasing in the stationary phase. Following co-cultivation with L. monocytogenes, the transcriptional level of luxS increased significantly in mid-exponential growing cells of L. acidophilus after incubation with viable L. monocytogenes cells and by addition of cell-free culture supernatant of L. monocytogenes, whereas incubation with heat killed cells of L. monocytogenes had no effect on the transcriptional level. This could indicate that the up-regulation of luxS is due to a response to a secreted compound produced by L. monocytogenes cells.
authors.affiliation: University of Copenhagen, Faculty of Life Sciences, Department of Food Science, Food Microbiology, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark. smje@life.ku.dk
authors.forename: Saloomeh
authors.initials: S
authors.lastname: Moslehi-Jenabian
authors.forename: Finn Kvist
authors.initials: FK
authors.lastname: Vogensen
authors.forename: Lene
authors.initials: L
authors.lastname: Jespersen
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001431:Bacteriological Techniques; D013437:Carbon-Sulfur Lyases / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D007779:Lactobacillus acidophilus / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D008089:Listeria monocytogenes / Q000254:growth & development* / Q000378:metabolism; D019936:Probiotics; D053038:Quorum Sensing; D015854:Up-Regulation
chemical_list: D001426:Bacterial Proteins; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria