Cryopreservation of Escherichia coli K12TG1: Protection from the damaging effects of supercooling by freezing

Abstract Injuries in living cells caused by water freezing during a freeze-thaw process have been extensively reported. In particular, intracellular water freezing has long been incriminated in cell death caused by a high cooling rate, but this supposition could not always be demonstrated. This work aims to discriminate the role of water freezing, dehydration and cold-induced injuries in cellular damage occuring during cryopreservation. For this purpose, Escherichia coli K12TG1 suspensions were maintained in a supercooled or frozen state at −20 °C for times ranging from 10 min to 5 h. The supercooled state was maintained for a long period at −20 °C by applying a non-injurious isostatic pressure ( P