title: Molecular characterization of class 3 integrons from Delftia spp.
abstract: Two environmental strains, Delftia acidovorans C17 and Delftia tsuruhatensis A90, were found to carry class 3 integrons, which have seldom been reported and then only from pathogens in which they are associated with antibiotic resistance genes. The Delftia integrons comprised a highly conserved class 3 integrase gene, upstream and oppositely oriented from a set of three or four gene cassettes that encoded unidentified functions. The A90 integron had one more gene cassette than the C17 integron, but the two were otherwise the same; furthermore, they were located within regions of sequence identity in both strains and linked to chromosomal genes. A screen of other Delftia and related strains did not reveal the presence of additional class 3 integrons. The observations suggest that these integrons were horizontally transferred to Delftia as part of a larger region and reside as chromosomal elements that probably predate transposon dissemination, as has been proposed for certain class 1 integrons.
authors.affiliation: Department of Microbiology and Immunology, Life Science Centre, University of British Columbia, 2350 Life Sciences Mall, Vancouver, British Columbia V6T 1Z3, Canada.
authors.forename: Hai
authors.initials: H
authors.lastname: Xu
authors.forename: Julian
authors.initials: J
authors.lastname: Davies
authors.forename: Vivian
authors.initials: V
authors.lastname: Miao
mesh_terms: D001483:Base Sequence; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D042742:Delftia / Q000235:genetics* / Q000302:isolation & purification; D005798:Genes, Bacterial; D019426:Integrases / Q000235:genetics; D032023:Integrons / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014871:Water Microbiology
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D019426:Integrases