Storage and revival of microorganisms

The Archaea and Bacteria are remarkably resistant to extreme conditions and many can desiccations or survive freezing without ill effect even in their vegetative states. This means that various but by no means all prokaryotes can be stored as pelleted biomass for decades. In the laboratory long-term storage of biomass frozen at -70∞C in a 50percent glycerol   solution is often used while this   can   sometimes cause cell death. Freezing in  dimethyl sulfoxide can  be  an  alternativ but  prokaryotes rarely  needs cryopreservation in  liquid nitrogen as  eukaryotic cells  can  do.  Larger laboratories may purchase a freeze-drying apparatus to lyophilize cultures. This is through far the most efficient technique of long-term storage. Short-term laboratory storage is normally done through streaking the biomass out onto solid media held in a suitable container.  After storage the cells are in a starved state and must be revived with a complex medium so as little stress as possible is placed on them.