Ejecting Bacteria from Biofilms: Microbial Minutes

What's Hot in the Microbial Sciences?

What do bacterial biofilms and jellyfish have in common? Perhaps more than you think.

Researchers recently found that biofilms can eject cells from their interior using a mechanism that is very similar to how jellyfish fire their stinging threads. But how exactly does this work—and why does it matter? Key takeaways and resources used in the Microbial Minutes are below.

Key Points

• Researchers discovered a previously unknown biofilm dispersal mechanism in Bacillus subtilis, in which cells are expelled from localized regions of the biofilm.
• The process is driven by gamma-polyglutamic acid (γ-PGA), a compound produced by cells within dispersal regions. Biofilms lacking γ-PGA were unable to carry out this localized cell release, demonstrating the molecule's essential role.The mechanism resembles how jellyfish and hydra fire their stinging organelles. In both systems, γ-PGA absorbs water and expands, generating physical forces that can propel stinging tubules outward.
• Experiments showed that preventing γ-PGA swelling with an osmolyte inhibited cell ejection, while overproducing γ-PGA created gaps within biofilms, indicating that expansion of the polymer physically pushes cells apart and drives dispersal.
• The findings suggest bacteria may use localized dispersal as a "bet-hedging" strategy, allowing some cells to explore new environments while others remain in the biofilm. The work also points to potential applications in promoting biofilm disruption to improve treatment of biofilm-associated infections.

Resources

The Paper

Chou T., et al. Self-generated hydrogel ejects bacterial cells for localized biofilm dispersion. Nature Microbiology, July 7, 2026. 

Additional Resources

Prinzi A. and Rhode. R.E. The Role of Bacterial Biofilms in Antimicrobial Resistance. asm.org, March 6, 2023. 

Berking S. and Herrmann K. Formation and discharge of nematocysts is controlled by a proton gradient across the cyst membrane. Helgoland Marine Research, Nov. 26, 2006. 

Park S., et al. The nematocyst's sting is driven by the tubule moving front. J R Soc Interface, March 1, 2017. 

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