Lyophilization, also known as freeze-drying or cryodesiccation, is the process of removing water from a product after it is frozen and placed under a vacuum, allowing the ice to change directly from solid to vapor without passing through a liquid phase. This lyophilization process is conducted in order to preserve perishables and extend shelf life, as well as making the materials more conveinent for transport and storage. Lyopyilized materials do not require refrigeration.
The process involves a freezing phase below the materials triple point. Then there is a sublimation phase to transition the material from a solid to a gas phase with no intermediate liquid stage. This is followed by the adsorbtion phase, during which the ionically-bound water molecules are removed.
Allow the vial to equilibrate to room temperature. Briefly centrifuge to ensure lyophilisate is collected at the bottom of the vial. Add volume of buffer needed to achieve concentration recommended. Allow vial to reconstitute for 15-30 min. at room temperature with gentle agitation.
Some steps are fundemental to lyophilize a sample during a batch process: Pretreatment formulation; loading in container (bulk, flask, vials); freezing (thermal treatment) at atmospheric pressure; primary drying (sublimation) under vacuum; secondary drying (desorption) under vacuum; backfill and stoppering (for sample in vials) under partial vacuum; removal of dried sample from freeze dryer. Successful lyophilization allows an extended shelf life and a product with a short reconstitution time with acceptable potency levels.
Take 0.1 to 0.2 mL of resuspended culture and streak direcly onto an appropriate agar plate. Make a dilution and spread on medium to check for purity of the culture. Then transfer the rest of the revived culture to an aprropriate liquid medium and incubate at the required teperature.