title: Multireplicon genome architecture of Lactobacillus salivarius.
abstract: Lactobacillus salivarius subsp. salivarius strain UCC118 is a bacteriocin-producing strain with probiotic characteristics. The 2.13-Mb genome was shown by sequencing to comprise a 1.83 Mb chromosome, a 242-kb megaplasmid (pMP118), and two smaller plasmids. Megaplasmids previously have not been characterized in lactic acid bacteria or intestinal lactobacilli. Annotation of the genome sequence indicated an intermediate level of auxotrophy compared with other sequenced lactobacilli. No single-copy essential genes were located on the megaplasmid. However, contingency amino acid metabolism genes and carbohydrate utilization genes, including two genes for completion of the pentose phosphate pathway, were megaplasmid encoded. The megaplasmid also harbored genes for the Abp118 bacteriocin, a bile salt hydrolase, a presumptive conjugation locus, and other genes potentially relevant for probiotic properties. Two subspecies of L. salivarius are recognized, salivarius and salicinius, and we detected megaplasmids in both subspecies by pulsed-field gel electrophoresis of sizes ranging from 100 kb to 380 kb. The discovery of megaplasmids of widely varying size in L. salivarius suggests a possible mechanism for genome expansion or contraction to adapt to different environments.
authors.affiliation: Department of Microbiology, Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland.
authors.forename: Marcus J
authors.initials: MJ
authors.lastname: Claesson
authors.forename: Yin
authors.initials: Y
authors.lastname: Li
authors.forename: Sinead
authors.initials: S
authors.lastname: Leahy
authors.forename: Carlos
authors.initials: C
authors.lastname: Canchaya
authors.forename: Jan Peter
authors.initials: JP
authors.lastname: van Pijkeren
authors.forename: Ana M
authors.initials: AM
authors.lastname: Cerdeño-Tárraga
authors.forename: Julian
authors.initials: J
authors.lastname: Parkhill
authors.forename: Sarah
authors.initials: S
authors.lastname: Flynn
authors.forename: Gerald C
authors.initials: GC
authors.lastname: O'Sullivan
authors.forename: J Kevin
authors.initials: JK
authors.lastname: Collins
authors.forename: Des
authors.initials: D
authors.lastname: Higgins
authors.forename: Fergus
authors.initials: F
authors.lastname: Shanahan
authors.forename: Gerald F
authors.initials: GF
authors.lastname: Fitzgerald
authors.forename: Douwe
authors.initials: D
authors.lastname: van Sinderen
authors.forename: Paul W
authors.initials: PW
authors.lastname: O'Toole
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D050260:Carbohydrate Metabolism; D004251:DNA Transposable Elements / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D016680:Genome, Bacterial; D007778:Lactobacillus / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010427:Pentose Phosphate Pathway / Q000235:genetics; D010457:Peptidoglycan / Q000096:biosynthesis; D010957:Plasmids / Q000235:genetics / Q000302:isolation & purification; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis; D011544:Pseudogenes; D012093:Replicon / Q000235:genetics*
chemical_list: D000596:Amino Acids; D004251:DNA Transposable Elements; D010457:Peptidoglycan; D011135:Polysaccharides, Bacterial