Mobile gene cassettes: a fundamental resource for bacterial evolution

Carolyn A. Michael*, Michael R. Gillings, Andrew J. Holmes, Lesley Hughes, Nigel R. Andrew, Marita P. Holley, H. W. Stokes

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

64 Citations (Scopus)
1 Downloads (Pure)


Horizontal gene transfer increases genetic diversity in prokaryotes to a degree not allowed by the limitations of reproduction by binary fission. The integron/gene cassette system is one of the most recently characterized examples of a system that facilitates horizontal gene transfer. This system, discovered in the context of multidrug resistance, is recognized in a clinical context for its role in allowing pathogens to adapt to the widespread use of antibiotics. Recent studies suggest that gene cassettes are common and encode functions relevant to many adaptive traits. To estimate the diversity of mobile cassettes in a natural environment, a molecular technique was developed to provide representative distributions of cassette populations at points within a sampling area. Subsequently, statistical methods analogous to those used for calculating species diversity were employed to assess the diversity of gene cassettes within the sample area in addition to gaining an estimate of cassette pool size. Results indicated that the number of cassettes within a 5 x 10-m sample area was large and that the overall mobile cassette metagenome was likely to be orders of magnitude larger again. Accordingly, gene cassettes appear to be capable of mobilizing a significant genetic resource and consequently have a substantial impact on bacterial adaptability.

Original languageEnglish
Pages (from-to)1-12
Number of pages12
JournalAmerican Naturalist
Issue number1
Publication statusPublished - Jul 2004

Bibliographical note

Copyright 2004 by University of Chicago Press. Originally published in The American naturalist.


  • integron
  • gene cassette
  • metagenome
  • horizontal gene transfer
  • diversity
  • jackknife

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