When would an endospore transform into its active form?
When an endospore develops, it is in direct reaction to a hostile or dangerous environmental change. One common cause is a reduction in nutrition, causing the bacteria to shed its most complex mechanisms; this allows it to become structurally resilient and require no outer energy to keep its potential. Once conditions change, the endospore is able to reproduce its original biological makeup with the patterns contained inside; endospores can remain dormant and viable for centuries. One thing that can cause an endospore to become active is the replacement of nutrition; with food and energy available, the endospore no longer needs to remain dormant. Another change could come from temperatures; if the bacteria needs a warm climate, cold weather could trigger the endospore's formation, and a warming climate will trigger the endospore's activation. One interesting thing is that an endospore is not a seed or reproductive agent; it is the original bacteria, stripped down to its essentials and in a state of stasis.
Endospores transform into an active form when the environmental conditions are favorable. Most bacteria prefer a moist area with constant temperature. When the environment changes into dryness or the temperature dramatically changes, the bacteria may die. There are types that can survive changes and go in a dormant state until the environment is favorable again.