Pyrococcus is morphologically similar to
Thermococcus.
Pyrococcus (the latin derivation literally means "fireball") differs from
Thermococcus primarily by its high temperature requirements;
Pyrococcus grows between 70 and 106°C with an optimum of 100°C.
Thermococcus and
Pyrococcus are also metabolically quite similar: Proteins, starch, or maltose are oxidized as electron donors and S
0 is the terminal acceptor and is reduced to H
2S.
Taken from the text Brock Biology of Microorganisms (10th ed.). Madigan, M.T., Martinko, J.M., and Parker, J. 2003. Prentice Hall. 458-459p.