Microalgae are of significant importance for future biotechnological applications. Many microalgae banks or laboratories attempt to maintain various microalgae for further research purposes. Cryopreservation has been preferred to reduce a labor-intensive and costly routine sub-culturing. Cryopreservation can also diminish the genetic drift risk. However, cryopreservation as a long term storage of microalgae method are still in developing progress because it cannot be generalized for all microalgae. Microalgae types, cryoprotectant agents (CPAs) types, freezing and thawing methods are the most important factors that should be considered for cryopreservation. In this short review the basic principles and the current advanced of microalgae cryopreservation methods are discussed with a suggested starting parameters for microalgae cryopreservation.

1. Introduction
2. Current Cryopreservation Technology
    2.1. Cell concentration, culture age, and centrifugation
    2.2. Freezing rate
    2.3. Cryoprotectants (CPAs)
3. Conclusions

• Wahyu Sri Kunto Nugroho(Department of Chemistry, Pukyong National University, Busan 48513, Korea)
• Do-A Kim(Department of Chemistry, Pukyong National University, Busan 48513, Korea)
• Dong-Woo Kim(Department of Chemistry, Pukyong National University, Busan 48513, Korea)
• Bon-Won Koo(Department of Chemistry, Pukyong National University, Busan 48513, Korea)
• Young Baek Hur(Southeast Sea Fisheries Research Institute, National Fisheries Research and Development Institute, Namhae 52440, Korea)
• Hak Jun Kim(Department of Chemistry, Pukyong National University, Busan 48513, Korea) Corresponding author