Seim, C.; Reineke, K.; Werner, S.; Dehlinger, A.; Legall, H.; Stiel, H.; Kanngießer, B.: High pressure treated Bacillus subtilis spores - Structural analysis by means of synchrotron and laboratory based soft X-ray microscopy. Innovative Food Science & Emerging Technologies 29 (2015), p. 134-142
10.1016/j.ifset.2015.03.010

Abstract:
Measurements were carried out on high pressure treated (HPT) bacterial endospores of the Bacillus subtilis strain PS832 by means of laboratory (LTXM) and synchrotron based transmission soft X-ray microscopy (SynchTXM). Using LTXM at 500 eV HPT spores could be identified by a higher transparency, due to dipicolinic acid (DPA) release from the spore's core, and their shriveled appearance caused by air-drying. Dormant spores were investigated at different photon energies at SynchTXM. Inner structures were visualized and it was shown that at a photon energy of 280 eV the micrographs yielded bigger absorption differences, and thus better contrast between the core/coat and the peptidoglycan-rich cortex. Tilt series of dormant and HPT spores were reconstructed. Virtual sections revealed the dormant spores' core, cortex and coat without the need to physically slice the sample. It was also possible to visualize the inside of the HPT spores, which proved to be void of DPA.