Visualization ofBacillus subtilisSpore Structure and Germination using Quick-Freeze Deep-Etch Electron Microscopy

Abstract

AbstractBacterial spores, known for their complex and resilient structures, have been the focus of visualization using various methodologies. In this study, we applied quick-freeze and replica electron microscopy techniques, allowing observation ofBacillus subtilisspores in high-contrast and three-dimensional detail. This method facilitated visualization of the spore structure with enhanced resolution and provided new insights into the spores and their germination processes. We identified and described five distinct structures: (i) hair-like structures on the spore surface, (ii) spike formation on the surface of lysozyme-treated spores, (iii) the fractured appearance of the outer spore cortex during germination, (iv) potential connections between small vesicles and the core membrane, and (v) the evolving surface structure of nascent vegetative cells during germination.