-80C Storage

We store many reagents and samples at -80C.  Clearly, this box of aliquots in our freezer has not been touched in a while!  Keeping samples at such a low temperature limits the activity of proteins and chemicals.  This is also the standard way to preserve isolated cell strains (in our case, E. coli carrying different plasmids and genes).  Cells are preserved in glycerol stocks to prevent the formation of ice crystals that would rupture cell walls.  Cells can be kept for months and years in this condition, always ready to be unfrozen and continue dividing.

Similar storage capabilities can be achieved, at least for cell free protein synthesis reactions, for a much smaller investment (freezers are expensive!).  Bundy et al. recently demonstrated lyophilization, freeze drying, can preserve cell extracts in a 4C fridge to ~60% viability of aqueous storage in -80C freezer.  Their set up could be purchased for around $3k while a reliable -80C freezer is around $10k.  They also found lyophilization reduces bacterial cell contamination in cell extracts.