Editing Endospore (section)

== Reactivation ==

Reactivation of the endospore occurs when conditions are more favourable and involves ''activation'', ''germination'', and ''outgrowth''. Even if an endospore is located in plentiful nutrients, it may fail to germinate unless activation has taken place. This may be triggered by heating the endospore. Germination involves the dormant endospore starting metabolic activity and thus breaking hibernation. It is commonly characterised by rupture or absorption of the spore coat, swelling of the endospore, an increase in metabolic activity, and loss of resistance to environmental stress.

Outgrowth follows germination and involves the core of the endospore manufacturing new chemical components and exiting the old spore coat to develop into a fully functional vegetative bacterial cell, which can divide to produce more cells.

Endospores possess five times more sulfur than vegetative cells. This excess sulfur is concentrated in spore coats as an amino acid, [[cysteine]]. It is believed that the macromolecule accountable for maintaining the dormant state has a protein coat rich in cystine, stabilized by S-S linkages. A reduction in these linkages has the potential to change the tertiary structure, causing the protein to unfold. This conformational change in the protein is thought to be responsible for exposing active enzymatic sites necessary for endospore germination.<ref>{{cite journal | last1 = Keynan | first1 = A. | last2 = Evenchik | first2 = Z. | last3 = Halvorson | first3 = H. O. | last4 = Hastings | first4 = J. W. | year = 1964 | title = Activation of bacterial endospores | journal = Journal of Bacteriology | volume = 88 | issue = 2| pages = 313–318 | pmid = 14203345 | pmc = 277301 | doi = 10.1128/JB.88.2.313-318.1964 }}</ref>

Endospores can stay dormant for a very long time. For instance, endospores were found in the tombs of the Egyptian pharaohs. When placed in appropriate medium, under appropriate conditions, they were able to be reactivated. In 1995, Raul Cano of California Polytechnic State University found bacterial spores in the gut of a fossilized bee trapped in amber from a tree in the [[Dominican Republic]]. The bee fossilized in amber was dated to being about 25 million years old. The spores germinated when the amber was cracked open and the material from the gut of the bee was extracted and placed in nutrient medium. After the spores were analyzed by microscopy, it was determined that the cells were very similar to ''[[Lysinibacillus sphaericus]]'' which is found in bees in the Dominican Republic today.<ref name=Pommerville/>