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Updated: Apr 27, 2026
Detection of Horizontal Gene Transfer Mediated by Natural Conjugative Plasmids in E. coli
Published on: March 24, 2023
Human intestinal cells modulate conjugational transfer of multidrug resistance plasmids between clinical Escherichia
Ana Manuel Dantas Machado1, Morten O A Sommer2
1Department of Systems Biology, Technical University of Denmark, Lyngby, Denmark.
Abstract:
Bacterial conjugation in the human gut microbiota is believed to play a major role in the dissemination of antibiotic resistance genes and virulence plasmids. However, the modulation of bacterial conjugation by the human host remains poorly understood and there is a need for controlled systems to study this process. We established an in vitro co-culture system to study the interaction between human intestinal cells and bacteria. We show that the conjugation efficiency of a plasmid encoding an extended spectrum beta-lactamase is reduced when clinical isolates of Escherichia coli are co-cultured with human intestinal cells. We show that filtered media from co-cultures contain a factor that reduces conjugation efficiency. Protease treatment of the filtered media eliminates this inhibition of conjugation. This data suggests that a peptide or protein based factor is secreted on the apical side of the intestinal cells exposed to bacteria leading to a two-fold reduction in conjugation efficiency. These results show that human gut epithelial cells can modulate bacterial conjugation and may have relevance to gene exchange in the gut.
Insights
Human gut cells can reduce bacterial conjugation, a key process for spreading antibiotic resistance. This study identifies a protein-based factor from intestinal cells that inhibits gene transfer between bacteria.
Area of Science:
- Microbiology
- Host-microbe interactions
- Genetics
Background:
- Bacterial conjugation facilitates the spread of antibiotic resistance genes and virulence factors within the gut microbiota.
- The influence of the human host on bacterial conjugation efficiency is not well understood.
- Controlled experimental systems are needed to investigate host modulation of bacterial gene exchange.
Purpose of the Study:
- To establish an in vitro system for studying bacterial conjugation with human intestinal cells.
- To determine if human intestinal cells modulate the conjugation efficiency of Escherichia coli.
- To identify host-derived factors that influence bacterial gene transfer.
Main Methods:
- Co-culture of clinical isolates of Escherichia coli with human intestinal cells in vitro.
- Analysis of plasmid conjugation efficiency using a plasmid encoding an extended-spectrum beta-lactamase.
- Filtration of co-culture media and protease treatment to identify inhibitory factors.
Main Results:
- Co-culture with human intestinal cells reduced the conjugation efficiency of Escherichia coli.
- Filtered co-culture media contained a factor that inhibited bacterial conjugation.
- Protease treatment abolished the inhibitory effect, indicating a protein-based factor.
- A peptide or protein secreted by intestinal cells reduced conjugation efficiency by twofold.
Conclusions:
- Human gut epithelial cells can actively modulate bacterial conjugation.
- A host-derived protein factor secreted apically inhibits bacterial gene transfer.
- These findings suggest a role for host cells in controlling the spread of antibiotic resistance in the gut.
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