Data for Ice recrystallization inhibiting polymers enable glycerol-free cryopreservation of microorganisms

Glycerol is the current gold-standard cryoprotectant, but it is intrinsically toxic to most microorganisms: only a fraction of cells survive freezing and the presence of glycerol can impact downstream applications and assays. Extremophile organisms survive repeated freeze/thaw cycles by producing antifreeze proteins which are potent ice recrystallization inhibitors.

Here we introduce a new concept for the storage/transport of microorganisms by using ice recrystallization inhibiting poly(vinyl alcohol) in tandem with poly(ethylene glycol). This cryopreserving formulation is shown to result in a 4-fold increase in E. coli yield post-thaw, compared to glycerol, utilizing lower concentrations, and successful cryopreservation shown as low as 1.1 wt % of additive. The mechanism of protection is demonstrated to be linked not only to inhibiting ice recrystallization (by comparison to a recombinant antifreeze protein) but also to the significantly lower toxicity of the polymers compared to glycerol.