Optimization of Cryopreservation Process Using Response Surface Methodology for Chlorella saccharophila and Chlorella zofingiensis

Abstract

The preservation of microalgae in a stable state is a fundamental requirement in pharmaceutical, agricultural, environmental sciences and different industries. Cryopreservation is widely stabilized for achieving long-term storage and has been applied to an increasingly diverse range of microalgae and cell cultures. The continuous storage of actively growing microalgae strains by routine serial subculture is relatively time-consuming and this technique has possible contamination risks. In this study, the optimization of cryopreservation process was carried out for two different Chlorella strains using response surface methodology (RSM) with three factors (cryoprotectant concentration, incubation time and cryopreservation time) including 19 runs. The optimal cell viability of C. zofingiensis was found at the dimethyl sulfoxide (DMSO) concentration of 12.89% at the incubation time of 8.14 min and with the cryopreservation time of 93.45 day, while C. saccharophila was found at the DMSO concentration of 12.86 % at the incubation time of 7.99 min and at cryopreservation time of 95.17 day.