Ultrastructural changes associated with germination and outgrowth of an appendage-bearing clostridial spore.

The sequence of events occurring during the germination and outgrowth of appendage-bearing spores of Clostridium bifermentans was studied by phase-contrast and electron microscopy. The mature spore was characterized ultrastructurally as having the normal spore components as well as long tubular appendages which orginated from the surface of the spore coat. Spores were incompletely enclosed by a distinctly laminated exosporium which possessed hairlike projections on its outermost layer. During germination, structural changes were observed in the core, core wall, cortex, and spore coat layers. Cortical material was extruded from the spore during outgrowth, which usually occurred from the pole opposite the appendages. The subunits comprising the structure of the appendages and the morphology of the mature appendages were observed. No discernible changes could be observed in the spore appendages during germination and outgrowth.