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Updated: Jun 25, 2026
07:34
Quantification of Interbacterial Competition using Single-Cell Fluorescence Imaging
Published on: September 2, 2021
A Type VII-secreted toxin enables inter-mycobacterial competition
Samuel T Benedict1,2, Kieran Bowran2, Eunice K E Lee2
1School of Biosciences, University of Birmingham, Birmingham, B15 2TT, UK.
Nature Communications
|June 23, 2026
Summary
Mycobacteria engage in inter-bacterial competition by secreting endo-D-arabinanases via the type VII secretion system (T7SS). This toxin targets the arabinogalactan layer of the cell wall, revealing a novel competitive mechanism in these bacteria.
Area of Science:
- Microbiology
- Bacterial Competition
- Cell Wall Biology
Background:
- Bacteria compete using secreted toxins, but this was uncharacterized in mycobacteria.
- The mycobacterial cell wall is unusually thick and protective, composed of peptidoglycan, arabinogalactan, and mycolic acids.
Purpose of the Study:
- To investigate inter-bacterial competition mechanisms in mycobacteria.
- To identify novel toxins and their targets within the mycobacterial cell envelope.
Main Methods:
- Structural biology and biochemistry were used to elucidate the mechanism of action.
- The type VII secretion system (T7SS) was identified as the secretion pathway for the toxin.
Main Results:
- Some mycobacteria secrete endo-D-arabinanases (GH183 family) for inter-bacterial competition.
- The toxin cleaves the arabinogalactan layer of the mycobacterial cell envelope.
- A protective protein family was identified, preventing self-toxicity.
Conclusions:
- Mycobacteria utilize T7SS-secreted endo-D-arabinanases for inter-bacterial warfare.
- This finding suggests widespread competition within the Mycobacteriales order.
- The study reveals a novel mechanism of bacterial competition involving cell wall degradation.
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