title: Ecological behavior of Lactobacillus reuteri 100-23 is affected by mutation of the luxS gene.
abstract: The luxS gene of Lactobacillus reuteri 100-23C was amplified by PCR, cloned, and then sequenced. To define a physiological and ecological role for the luxS gene in L. reuteri 100-23C, a luxS mutant was constructed by insertional mutagenesis. The luxS mutant did not produce autoinducers AI-2 or AI-3. Complementation of the luxS mutation by a plasmid construct containing luxS restored AI-2 and AI-3 synthesis. In vitro experiments revealed that neither the growth rate, nor the cell yield, nor cell survival in the stationary phase were compromised in the luxS mutant relative to the wild type and complemented mutant. The ATP content of exponentially growing cells of the luxS mutant was, however, 65% of that of wild-type cells. Biofilms formed by the luxS mutant on plastic surfaces in a bioreactor were thicker than those formed by the wild type. Biofilm thickness was not restored to wild-type values by the addition of purified AI-2 to the culture medium. In vivo experiments, conducted with ex-Lactobacillus-free mice, showed that biofilms formed by the mutant strain on the epithelial surface of the forestomach were approximately twice as thick as those formed by the wild type. The ecological performance of the luxS mutant, when in competition with L. reuteri strain 100-93 in the mouse cecum, was reduced compared to that of a xylA mutant of 100-23C. These results demonstrate that LuxS influences important ecological attributes of L. reuteri 100-23C, the consequences of which are niche specific.
authors.affiliation: Department of Microbiology and Immunology, University of Otago, PO Box 56, Dunedin, New Zealand. gerald.tannock@stonebow.otago.ac.nz
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Tannock
authors.forename: Salina
authors.initials: S
authors.lastname: Ghazally
authors.forename: Jens
authors.initials: J
authors.lastname: Walter
authors.forename: Diane
authors.initials: D
authors.lastname: Loach
authors.forename: Heather
authors.initials: H
authors.lastname: Brooks
authors.forename: Gregory
authors.initials: G
authors.lastname: Cook
authors.forename: Michael
authors.initials: M
authors.lastname: Surette
authors.forename: Cameron
authors.initials: C
authors.lastname: Simmers
authors.forename: Phil
authors.initials: P
authors.lastname: Bremer
authors.forename: Fabio
authors.initials: F
authors.lastname: Dal Bello
authors.forename: Christian
authors.initials: C
authors.lastname: Hertel
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D018441:Biofilms; D013437:Carbon-Sulfur Lyases; D017931:DNA Primers; D017753:Ecosystem; D005816:Genetic Complementation Test; D052200:Limosilactobacillus reuteri / Q000235:genetics / Q000502:physiology*; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria