title: The virulence plasmid of Salmonella typhimurium is self-transmissible.
abstract: Most isolates of Salmonella enterica serovar Typhimurium contain a 90-kb virulence plasmid. This plasmid is reported to be mobilizable but nonconjugative. However, we have determined that the virulence plasmid of strains LT2, 14028, and SR-11 is indeed self-transmissible. The plasmid of strain SL1344 is not. Optimal conjugation frequency requires filter matings on M9 minimal glucose plates with a recipient strain lacking the virulence plasmid. These conditions result in a frequency of 2.9 x 10(-4) transconjugants/donor. Matings on Luria-Bertani plates, liquid matings, or matings with a recipient strain carrying the virulence plasmid reduce the efficiency by up to 400-fold. Homologs of the F plasmid conjugation genes are physically located on the virulence plasmid and are required for the conjugative phenotype.
authors.affiliation: Department of Molecular Microbiology and Immunology, Oregon Health Sciences University, Portland, Oregon 97201-3098, USA. ahmerb@ohsu.edu
authors.forename: B M
authors.initials: BM
authors.lastname: Ahmer
authors.forename: M
authors.initials: M
authors.lastname: Tran
authors.forename: F
authors.initials: F
authors.lastname: Heffron
mesh_terms: D003227:Conjugation, Genetic; D005144:F Factor / Q000235:genetics; D005798:Genes, Bacterial; D010957:Plasmids / Q000235:genetics*; D012486:Salmonella typhimurium / Q000235:genetics* / Q000472:pathogenicity*; D014774:Virulence / Q000235:genetics