Figure 2: Bacterial spore structure. From the inner to the outer: a) nuclear material and b) inner membrane constitute the core of the spore; c) cortex protect the spore from high temperature and maintain the core in a dehydrated state; an d) outer membrane divide the cortex from the e) protein coat, which is involved in germination and in conferring spore resistance to heat and chemical agents. Exosporium, a facultative external structure present only in some bacterial spores, plays a role in the protection of the spore and in its environmental interactions.