title: Megaplasmids encode differing combinations of lantibiotics in Streptococcus salivarius.
abstract: Streptococcus salivarius strains commonly produce bacteriocins as putative anti-competitor or signalling molecules. Here we report that bacteriocin production by the oral probiotic strain S. salivarius K12 is encoded by a large (ca. 190 kb) plasmid. Oral cavity transmission of the plasmid from strain K12 to a plasmid-negative variant of this bacterium was demonstrated in two subjects. Tests of additional S. salivarius strains showed large (up to ca. 220 kb) plasmids present in bacteriocin-producing isolates. Various combinations (up to 3 per plasmid) of loci encoding the known streptococcal lantibiotics salivaricin A, salivaricin B, streptin and SA-FF22 were localised to these plasmids. Since all bacteriocin-producing strains of S. salivarius tested to date appear to harbour plasmids, it appears that they may function as mobile repositories for bacteriocin loci, especially those of the lantibiotic class.
authors.affiliation: BLIS Technologies Ltd., Centre for Innovation, University of Otago, PO Box 56, Dunedin, 9001, New Zealand.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Wescombe
authors.forename: Jeremy P
authors.initials: JP
authors.lastname: Burton
authors.forename: Peter A
authors.initials: PA
authors.lastname: Cadieux
authors.forename: Nikolai A
authors.initials: NA
authors.lastname: Klesse
authors.forename: Otto
authors.initials: O
authors.lastname: Hyink
authors.forename: Nicholas C K
authors.initials: NC
authors.lastname: Heng
authors.forename: Chris N
authors.initials: CN
authors.lastname: Chilcott
authors.forename: Gregor
authors.initials: G
authors.lastname: Reid
authors.forename: John R
authors.initials: JR
authors.lastname: Tagg
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001430:Bacteriocins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics* / Q000378:metabolism; D013291:Streptococcus / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D001430:Bacteriocins; D010455:Peptides; C435721:streptin; C082674:salivaricin A; C016887:A-FF22