Glassy state in Bacillus subtilis spores analyzed by differential scanning calorimetry

• Published in: International journal of food microbiology 2006-02, Vol.106 (3), p.286-290
• Main Authors: Stecchini, Mara Lucia, Del Torre, Manuela, Venir, Elena, Morettin, Alessia, Furlan, Patrizia, Maltini, Enrico
• Format: Article
• Language: English
• Subjects: Bacillus subtilis; Bacillus subtilis - growth & development; Bacillus subtilis - isolation & purification; Bacillus subtilis - physiology; Biological and medical sciences; Calorimetry, Differential Scanning - methods; DSC; Food industries; Food Microbiology; Fundamental and applied biological sciences. Psychology; Glass transition; Hot Temperature; Kinetics; Models, Biological; Spores, Bacterial - isolation & purification; Spores, Bacterial - physiology; Spores, Bacterial - ultrastructure
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2005.06.028

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 volume-activated 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.