Plasmids from freshwater enironments capable of IncQ retrotransfer are diverse and include pQKH54, a new IncP-1 subgroup archetype

Research output: Contribution to journalArticle


  • P Akhtar
  • Karen Jones
  • CD Perkins
  • JR Williams
  • MJ Day
  • JC Fry

Colleges, School and Institutes


Nine mercury-resistance plasmids isolated from river epilithon were assessed for their ability to retrotransfer the non-conjugative IncQ plasmid, R300B, derivatives of which have commercial uses that may result in accidental or deliberate release into the environment. Retrotransfer frequencies ranging from 2(.)1 x 10(-4) to 1(.)75 x 10(-5) were obtained for five of the nine plasmids - the remaining plasmids showed low or undetectable retrotransfer ability. The majority of the retrotransfer-proficient plasmids could not be classified by the tests used. Classical incompatibility testing with RP4 identified pQKH6, pQKH54 and pQM719 as IncP-1. Hybridization to replicon probes confirmed this for pQKH6 and pQM719 and added pQKH33. PCR with primers designed to amplify trfA and korA regions of IncP-1 plasmids did not identify any other plasmids. Plasmids pQKH6 and pQM719 but not pQKH54 produced similar SphI restriction profiles to the IncP-1 beta subgroup. The complete nucleotide sequence of pQKH54 was determined, revealing it to have a complete IncP-1 backbone but belonging to a new distinct subgroup which was designated IncP-1 gamma. The results emphasize the ubiquity and diversity of IncP-1 plasmids in the environment but demonstrate that plasmids of as yet unknown groups are also able to retrotransfer IncQ plasmids efficiently.


Original languageEnglish
Pages (from-to)2689-2701
Number of pages13
Publication statusPublished - 1 Sep 2006