Development of Alternative Technology for the Long-term Storage of Microalgal Stock Culture in Fish Hatcheries

Maintenance of algal culture faces several problems associated with climate change, contaminations, equipment failures, power failures, unexplained crashes, poor lab facilities. Microalgae are traditionally preserved by serial subculture methods that are laborious, costly, and high risk of culture contamination. While unique characteristics may not be durably maintained with general subculture, cryopreservation methods better prevent alterations from desired characteristics. Because of the cost-effective in replacing of liquid nitrogen at every interval of time and technical person needed for the preservation. The objective is to find out an alternative and a low-cost technology for the preservation of microalgae Stock culture. The microalgae Nannochloropsis salina, Chlorella volutis, Cheatoceros gracilis, Dunaliella sp. and Amphora sp., were preserved using common cryoprotectants (methanol, DMSO, ethylene glycol and glycerol) for 6 months at –196°C and –20°C. The viabilities of the microalgae were assessed after thawing, and cell counts were measured. The preserved algae Nannochloropsis salina, Chlorella volutis, Dunaliella sp. and Amphora sp. evoked good responses with negligible changes in their survivability in 6 months incubation period when preserved at –20°C and – 196°C, while the Cheatoceros gracilis regenerate only in –196°C but not restored in –20°C. In this study, an alternative method for liquid nitrogen preservation has been standardized and this new method can be a boon for small level fish hatcheries and microalgal stock holders.