Embedded Dehydration Cryopreservation Three Bait Golden Algae Research

Pavlova viridis, Isochrysis zhanjiangensis and Isochrysis galbana 3011 were cryopreserved in liquid nitrogen using encapsulation-dehydration.Algal cells in early stationary phase were encapsulated in 3% Ca-alginate beads with 30‰ NaCl,2 million cells in one bead.Beads were desiccated with silica gel then directly immersed in liquid nitrogen.The cell viability after warming was evaluated by chlorophyll content.The main factors influencing the cell viability, such as water content of beads, dehydration rate, dehydration procedure, preculture and recovery methods after thawing were studied.The results are as follows:1. Effect of water content on cell viabilityAt an average dehydration rate of 0.9% water content/h,water contents in beads had more effects on cell viability after dehydration than after thawing. Different algae have various optimum water contents. The highest viability of Pavlova viridis reached 69% when it was dehydrated to 35% water content. As to other two algae, 30% water content is optimum.Their highest viabilities are 10% and 13% respectively.2. Effect of dehydration rate At different dehydration rates ( a water reduction per hour 0.3%, 0.7%, 0.9%, 1.1%, 2%,13%), three algae all obtained highest viabilities at the dehydration rate of 0.9% water content/h.3. Effect of dehydration procedure Beads of Pavlova viridis were desiccated with four different procedures.Two dehydration rates were used, which are 0.9% water content/h (slow) and 10% water content/h(rapid).Resul-ts showed that slow dehydration is the best.A dehydration combination of rapid dehydration to 70% water content ,followed by slow dehydration to the optimum water content is a better procedure.Rapid dehydration is the worst.4. Effect of preculture Beads were encapsulated and incubated in culture medium containing 2% PEG and 5% PVP respectively for 90 min before dehydration.Cell viability of Pavlova viridis was increased by 6% after freezing.Preculture had less effect on cell viabilities of other two algae.5. Effect of recovery methods after thawing After thawing, the highest viability was obtained when beads of Pavlova viridis were incubated in culture medium for 48h in darkness at room temperature. As to other two algae,the suitable recovery method was to incubate beads over saturated NaCl solution in a closed jar for 12h in darkness at room temperature.