Physical basis for the adaptive flexibility of Bacillus spore coats Journal Article

Authors: Sahin, O; Yong, E. H.; Driks, A; Mahadevan, L
Article Title: Physical basis for the adaptive flexibility of Bacillus spore coats
Abstract: Bacillus spores are highly resistant dormant cells formed in response to starvation. The spore is surrounded by a structurally complex protein shell, the coat, which protects the genetic material. In spite of its dormancy, once nutrient is available (or an appropriate physical stimulus is provided) the spore is able to resume metabolic activity and return to vegetative growth, a process requiring the coat to be shed. Spores dynamically expand and contract in response to humidity, demanding that the coat be flexible. Despite the coat's critical biological functions, essentially nothing is known about the design principles that allow the coat to be tough but also flexible and, when metabolic activity resumes, to be efficiently shed. Here, we investigated the hypothesis that these apparently incompatible characteristics derive from an adaptive mechanical response of the coat. We generated a mechanical model predicting the emergence and dynamics of the folding patterns uniformly seen in Bacillus spore coats. According to this model, spores carefully harness mechanical instabilities to fold into a wrinkled pattern during sporulation. Owing to the inherent nonlinearity in their formation, these wrinkles persist during dormancy and allow the spore to accommodate changes in volume without compromising structural and biochemical integrity. This characteristic of the spore and its coat may inspire design of adaptive materials.
Journal Title: Journal of the Royal Society, Interface / the Royal Society
Volume: 9
Issue: 76
ISSN: 1742-5662; 1742-5662
Publisher: Unknown  
Journal Place: England
Date Published: 2012
Start Page: 3156
End Page: 3160
Language: eng
Notes: LR: 20130416; JID: 101217269; OID: NLM: PMC3479929 [Available on 11/07/13]; PMCR: 2013/11/07 00:00; 2012/08/01 [aheadofprint]; ppublish