Stability of biotransformation capacity in Digitalis lanata cell cultures after cryogenic storage.

Suspension cultures of Digitalis lanata were stored at the temperature of liquid nitrogen. After thawing, viable cultures were recovered which showed a growth rate equal to that of untreated cells. The capacity of Digitalis cells to transform β-methyldigitoxin to β-methyldigoxin remained unchanged after cryostorage. This was shown in 300-ml shake cultures as well as in 20-1 bioreactors. From these results it is clear that cryostorage is a suitable method for preserving cell lines with specific capacities to produce compounds of medical and industrial importance.