Final answer:
Endospore-forming bacteria start producing endospores when they reach a certain level of maturity, which can vary depending on the species and environmental conditions.
Step-by-step explanation:
The cultures of endospore-forming bacteria can start producing endospores when they reach a certain level of maturity. The exact age at which this occurs can vary depending on the specific species of bacteria as well as environmental conditions. However, Mature endospores can be highly resistant and can survive for long periods of time. When favorable conditions are present, the endospores can germinate and become active again.
For example, endospores of certain species have been shown to persist in a dormant state for extended periods, up to thousands of years. However, when more favorable conditions are present, such as the availability of water and nutrients, the endospores can germinate and return to an active state as vegetative cells, capable of growth and reproduction.