What is the main characteristic of spores in bacteria?

Bacterial spores, also known as endospores, are remarkable structures that enable bacteria to survive under extreme conditions. The primary characteristic that defines spores is their resistance to environmental stresses such as heat, desiccation (drying), radiation, and chemical agents, including disinfectants. This resistance is due to the durable outer layers of the spore, which protect the genetic material and essential cellular components inside.

When environmental conditions become unfavorable for growth, such as in high temperatures or lack of nutrients, some bacteria can enter a dormant spore state. In this form, they can withstand harsh conditions that would normally kill the bacteria in their active state. Once conditions improve, these spores can germinate and return to their vegetative state, allowing the bacteria to grow and reproduce again.

In contrast, the other options reflect characteristics that do not accurately describe bacterial spores. Spores do not reproduce quickly; instead, they provide a means of survival during adverse conditions. They are not typically susceptible to antibiotics; in fact, their structure often allows them to survive antibiotic treatment. Lastly, while moisture is essential for the growth of bacterial cells, spores can actually survive in dry conditions that would be lethal to vegetative cells.