Thermal properties of dried spores of Bacillus subtilis, investigated by differential scanning calorimetry (DSC), were studied. A reversible heat
capacity shift ascribable to glass–rubber transition was observed at 90–115 -C. The transition was found to be a pressure-inhibited volumeactivated
event. The decoated spores and the extracted peptidoglycan material exhibited glass transition, suggesting that the cortex could be
involved in the event. Furthermore, the glass transition was evident when spores were treated with strong acid, and when the isogenic strain PS578
was scanned, indicating that core integrity and core components are not involved in the occurrence of the event. These results suggest that in the
dried B. subtilis spores an amorphous biomaterial, possibly the cortex peptidoglycan, is present as a glass.
