I prepared a 5 gms of bacterial cells suspended in PBS (phosphate buffer saline) and placed it in -4 degree (to preserve), now I want to lyophilize my cells.
the problem is :
1- I need to change the PBS for a safer freeze-drying buffer(like sucrose), so I will need to thaw and centrifuge again. I don't know if this could affect the viability of the cells?
2- is it safe to perform freeze-drying using PBS as a freeze-drying buffer?
The freezing of bacterial solution at -4°C following by thawing step affects the viability of cells due to the formation of large ice particles inside the cytoplasm which can damage the integrity of the cell.
la congélation à -4 °C est une congélation lente, donc il y aura formation de gros cristaux de glace à l'intérieur et à l'extérieur des cellules bactériennes et lors de la décongélation, il y aura rupture des membranes donc la viabilité des cellules sera affectée.
As a general rule, the viable storage period of bacteria increases as the storage temperature decreases. Once the temperature is below the freezing point, however, cryoprotectants are essential to reduce cell damage caused by the freezing process. The specific length of time that culture will remain viable in a given storage condition is dependent upon the bacterial strain. Cell death during storage is inevitable but should be minimized as much as possible, which can sacrifice ease of use. Bacterial cultures that are used regularly (i.e., daily/weekly) can be stored on agar plates or in stab cultures in a standard refrigerator at 4°C. If cultures will not be used for more than a few weeks, though, more long-term storage methods should be considered for maximum bacterial viability.
You can also follow the following links
Article Characterization of Phosphate Buffered Saline (PBS) in Froze...
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