Cryopreservation of the microalgae Chaetoceros calcitrans and its effects on growth and biochemical composition

In this study, in order to evaluate the possibility of cryopreservation of C. calcitrans, 4 cryoprotectant agents (dimethyl sulfoxide, methanol, glycerol and ethylene glycol), each with different concentrations (2.5, 5, 10, 15, 20, 25% (v/v)), were taken as experimental treatments. Then, microalgae samples were placed at -196°C for 30 days. After that, in order to determine the best treatments, re-cultivation of microalgae was carried out and growth performance, biochemical composition and fatty acid profile were measured. After thawing, regrowth of microalgae cells was observed in 15 out of 24 treatments. The highest final cell density (4.13x106 cells/ml) was observed in DMSO15. After thawing, in the treatments in which the cells were reproduced again, the viability ranged between 8.26 and 28.19 percent. Maximum viability index were recorded in DMSO15, DMSO10 and ME15, respectively. Biochemical composition analysis showed that there was a significant increase on the lipid content in the experimental treatments compared to the control group (p<0.05). No significant difference was observed on the fatty acid profile(p>0.05). The results showed that the cryopreservation of C. calcitrans can be successful only if we use DMSO (5-15%) or ME (10-15%) as a cryoprotectant, and the best results are obtained when using DMSO at the level of 15%.