title: Characterization of a small cryptic plasmid from Salmonella enteritidis that affects the growth of Escherichia coli.
abstract: We examined the plasmid content of 25 clinical isolates of Salmonella enteritidis, and detected the presence of small plasmids (3-5.3 kb) in 9 of them, alone, or in addition to the large, so-called virulence plasmid. A 5.3-kb plasmid isolated as unique extrachromosomal DNA from a strain responsible for a high-mortality outbreak was characterized by restriction mapping and cloning. The plasmid replicon was localized in a 1.7-kb fragment, that hybridized with three of the small plasmids detected in S. enteritidis, and with another small plasmid from Salmonella typhimurium. A strain of Escherichia coli carrying this plasmid, or a cloned 3.7-kb PvuII restriction fragment, showed a slower growth rate, especially in minimal medium, as well as a noticeable increase in DNA methyltransferase activity.
authors.affiliation: Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Ibáñez
authors.forename: R
authors.initials: R
authors.lastname: Rotger
mesh_terms: D015139:Blotting, Southern; D003001:Cloning, Molecular; D015254:DNA Modification Methylases / Q000378:metabolism; D004261:DNA Replication; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development*; D006801:Humans; D010957:Plasmids; D015183:Restriction Mapping; D012480:Salmonella Infections / Q000382:microbiology; D012477:Salmonella enteritidis / Q000235:genetics*
chemical_list: D015254:DNA Modification Methylases