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Updated: Jan 10, 2026

Detection of Horizontal Gene Transfer Mediated by Natural Conjugative Plasmids in E. coli
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Detection of Horizontal Gene Transfer Mediated by Natural Conjugative Plasmids in E. coli

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Megaplasmids associate with Escherichia coli and other Enterobacteriaceae

Allison K Guitor1,2, Shuai Wang2, Owen T Tuck2,3

  • 1Department of Earth and Planetary Sciences, University of California, Berkeley, CA, USA.

Biorxiv : the Preprint Server for Biology
|November 24, 2025
PubMed

Insights

Researchers discovered large bacterial plasmids, called megaplasmids, in human and animal guts. These self-transmissible elements may enhance bacterial survival and spread, impacting both beneficial and pathogenic bacteria.

Area of Science:

  • Microbiology
  • Genomics
  • Bacterial Pathogenesis

Background:

  • Enterobacteriaceae are common bacteria in humans and animals, including pathogens.
  • Plasmids are mobile genetic elements that can carry advantageous genes.

Purpose of the Study:

  • To report the discovery and characterization of large Enterobacteriaceae megaplasmids.
  • To investigate the potential functions and mobility of these megaplasmids.

Main Methods:

  • Analysis of complete plasmid genomes.
  • Genome modification pattern analysis to link plasmids to host species.
  • Identification of conjugation machinery and tRNA content.

Main Results:

  • Discovered Enterobacteriaceae megaplasmids up to 1.58 Mbp in infant and adult guts.
  • Identified plasmids linked to E. coli, Citrobacter, and Enterobacter species.
  • Plasmids possess conjugation machinery, suggesting self-transmission and broad host range.
  • Plasmids encode multi-drug efflux systems, secreted effectors, and numerous tRNA variants.

Conclusions:

  • These megaplasmids are likely self-transmissible with a broad host range.
  • The coding capacity of these megaplasmids may enhance bacterial competitiveness and survival.
  • Plasmids may play a role in controlling other genetic elements and host cell death.
Keywords:
EnterobacteriaceaeEscherichia coliPlasmidsSalmonella entericaantibiotic resistancehuman gut microbiomemegaplasmidsmethylationpreterm infantssecretion systemsvirulence

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