Bacteria residing in the large intestine release which is absorbed by the human host and used for the process of blood clotting.

Vitamin K

Explanation:

Vitamin K is ingested, stored by friendly bacteria found in our gastrointestinal tract till its needed. Bacteria releases it and is absorbed by small intestine and liver to help in coagulation and bone metabolism.

It works as a coenzyme during the conversion of inactive zymogens produced by the liver (clotting factors) to prothrombin. Vitamin K aids enzyme carboxylase in catalysing the carboxylation of glutamic residue reactions. Prothrombin is vitamin K-dependent clotting factor that activates into thrombin then fibrinogen. Without vitamin K there will be no blood clotting and will bleed to death.