Bacterial spores respond to humidity similarly to hydrogels

Gennady Y. Gor, George W. Scherer, Howard A. Stone

Research output: Contribution to journalArticlepeer-review


Bacterial spores have outstanding properties from the materials science perspective, which allow them to survive extreme environmental conditions. Recent work by [S. G. Harrellson et al., Nature 619, 500–505 (2023)] studied the mechanical properties of Bacillus subtilis spores and the evolution of these properties with the change of humidity. The experimental measurements were interpreted assuming that the spores behave as water-filled porous solids, subjected to hydration forces. Here, we revisit their experimental data using literature data on vapor sorption on spores and ideas from polymer physics. We demonstrate that upon the change of humidity, the spores behave like rubber with respect to their swelling, elasticity, and relaxation times. This picture is consistent with the knowledge of the materials comprising the bacterial cell walls—cross-linked peptidoglycan. Our results provide an interpretation of the mechanics of bacterial spores and can help in developing synthetic materials mimicking the mechanical properties of the spores.

Original languageEnglish (US)
Article numbere2320763121
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number10
StatePublished - Mar 5 2024

All Science Journal Classification (ASJC) codes

  • General


  • absorption
  • adsorption
  • bacterial spores
  • hydrogel
  • swelling


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