Long-term Preservation of Micro-algal Stock for Fish Hatcheries

Abstract

Aquaculture is a fast-growing sector with a high scope for augmentation. Microalgae are frequently used for fish larvae culture. Hatcheries face many problems regarding the maintenance of a stock culture of the microalgae. Long term maintenance of microalgal species by serial sub culturing is often expensive, time-consuming and leads to genetic change. The present study is aimed to develop an alternative method for the long-term preservation of stock cultures. In this research, the cryopreservation protocol has been used for the preservation of Nannochloropsis sp at – 20° C using two criteria as different concentration of internal (Me2SO, MeOH, glycerol and ethylene glycol), external cryoprotectants (sucrose and sorbitol) and equilibration time (30 and 60 minutes). The results showed that the preservation of Nannochloropsis sp is feasible using this methodology. The present study proved that 10 % of Me2SO had the maximum viability at 30 minutes equilibration time and that the same concentration of cryoprotectant had resulted in the maximum viability after 6 months of preservation. From the study, it is evident that the microalgae can be preserved for a long time without using liquid nitrogen.

Keywords

• Hatchery
• Preservation
• Nannochloropsis
• Cryoprotectants
• Equilibration time