Modeling and design of algal cryopreservation protocols

Cryopreservation has been advocated as a preferential method for the long term storage of over 2200 algal cultures currently in reserve in The Culture Collection of Algae at the University of Texas at Austin. Traditional methods for developing freezing protocols rely heavily upon empirical findings to determine critical freezing parameters necessary to achieve acceptable survival rates. An alternative and more insightful method for designing optimal freezing procedures may be achieved with the use of computer-based models to simulate the physical processes encountered during cryopreservation.;The primary goal of this research was to develop a set of computer-based models to simulate the biophysical response of algal cells during specific phases of cryopreservation. An osmotic response model was generated to simulate the volumetric response of the algal cell to the addition and removal of cryoprotective additives (CPAs) over a temperature range from 25;Cryopreservation parameters for an optimal protocol were selected from the results of a rational multi-step design process performed with the osmotic response and IIF models. Viability data previously collected from osmotic and freezing experiments provided critical information that guided the selection of protocol parameters that avoided hazardous conditions and maintained cellular responses within safe physiological limits. Cell survival rates obtained with the optimized freezing parameters for C. texanum were equal to the viability results achieved with an experimentally developed protocol. Results from this study indicate that the computer models developed here can be used as an effective tool for providing insightful information in the development of optimal cryopreservation protocols for algae.