ABSTRACT
The strain IPPAS H-242 is an eustigmatophycean alga with good growth characteristics and high content of the long chain polyunsaturated eicosapentaenoic fatty acid (EPA) - a very-long-chain fatty acid with high nutraceutical value. In this study, based on 18S rRNA gene and ITS1-5.8S-ITS2 sequences the strain IPPAS H-242 was identified as an authentic strain of Vischeria punctata. The effect of salt stress (0.5 M NaCl) on growth, cell morphology, ultrastructure, and biochemical composition with the emphasis on the fatty acid (FA) profile was investigated in batch cultures. Under salt stress, biomass accumulation and cell division were severely inhibited; cells were bigger, with higher chloroplast volume and numerous mitochondria, they had more proteins (73 % from the initial concentration as compared to 23 % in control) and their lipids had higher EPA proportion (13.6 % of total FA as compared to 6.4 % of total FA in control). In salt-stressed cells, thylakoid organization and photosynthetic activity were impaired, and D1 protein content decreased to trace amounts. In spite of an increase in EPA proportion in total FA, salt stress causes a decrease in total EPA productivity (49 mg/L as compared to 130 mg/L in control).