title: Spreading antibiotic resistance through spread manure: characteristics of a novel plasmid type with low %G+C content.
abstract: Bioactive amounts of antibiotics as well as resistant bacteria reach the soil through manure fertilization. We investigated plasmids that may stimulate the environmental spread and interspecies transfer of antibiotic resistance. After treatment of two soils with manure, either with or without the sulfonamide antibiotic sulfadiazine, a significant increase in copies of the sulfonamide resistance gene sul2 was detected by qPCR. All sul2 carrying plasmids, captured in Escherichia coli from soil, belonged to a novel class of self-transferable replicons. Manuring and sulfadiazine significantly increased the abundance of this replicon type in a chemically fertilized but not in an annually manured soil, as determined by qPCR targeting a transfer gene. Restriction patterns and antibiograms showed a considerable diversity within this novel plasmid group. Analysis of three complete plasmid sequences revealed a conserved 30 kbp backbone with only 36% G+C content, comprised of transfer and maintenance genes with moderate homology to plasmid pIPO2 and a replication module (rep and oriV) of other descent. The plasmids differed in composition of the 27.0-28.3 kbp accessory region, each of which carried ISCR2 and several resistance genes. Acinetobacter spp. was identified as a potential host of such LowGC-type plasmids in manure and soil.
authors.affiliation: Julius Kühn-Institute - Federal Research Centre for Cultivated Plants (JKI), Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany. holger.heuer@jki.bund.de
authors.forename: Holger
authors.initials: H
authors.lastname: Heuer
authors.forename: Christoph
authors.initials: C
authors.lastname: Kopmann
authors.forename: Chu T T
authors.initials: CT
authors.lastname: Binh
authors.forename: Eva M
authors.initials: EM
authors.lastname: Top
authors.forename: Kornelia
authors.initials: K
authors.lastname: Smalla
mesh_terms: D000150:Acinetobacter / Q000187:drug effects* / Q000235:genetics*; D001482:Base Composition; D017124:Conserved Sequence; D016172:DNA Fingerprinting; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D023061:Gene Order; D014644:Genetic Variation; D008372:Manure / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA; D026801:Synteny
chemical_list: D004269:DNA, Bacterial; D008372:Manure