Cryopreservation of Cryophilic Chlorophyta Pyramimonas sp (KOPRI AnM0046)

Abstract

Korea Polar Research Institute (KOPRI) has polar microalgae culture collection. Korea Culture Collection of Polar Microorganisms (KCCPM) is a Korean collection of psychrophilic microorganisms from the Antarctic and Arctic. Polar psychrophiles, which thrive under extreme conditions such as temperature, salinity, and light, are novel targets for biotechnology. Presently, microalgae cultures are maintained by serial cultures. However, continuous serial cultures may cause genetic drift and many chances for contamination. Since long-term preservation of these organisms has many advantages, cryopreservation was employed to some microalgae. So far, tested were Porosira sp. (AnM0008), Navicula sp. (ArM0002), Pyramimonas sp. (KOPRI AnM0046). KOPRI AnM 0008 and AnM0046 were obtained from Maxwell Bay, King George Island, Antarctica, while ArM 0002 from Svalbard island, Norway. Cryopreservation of only Chlorophyta AnM0046 was met with some success. This species produces ice-active substances (IAS) and therefore has ice-controlling activity. Cryoprotectants (CPAs) and freezing protocol were screened and optimized. As a result, the toxicity of CPAs used was observed over 30%. Cryopreservation of KOPRI AnM0046 was carried out in the presence of CPAs by (a) direct freezing in liquid nitrogen and (b) controlled freezing using a controlled rate freezer followed by storage in the LN2 tank. KOPRI AnM0046 strain survived after both uncontrolled direct freezing and modified freezing.