Effect of Different Concentrations of NaCl on Growth and Biochemical Characteristics of Red Microalga Porphyridium cruentum

The red microalga Porphyridium cruentum is a potential source of valuable biologically active com¬pounds. This microalga is easily cultivated and could change its growth and biochemical composition in response to environmental variations. The effect of growth medium content, especially salinity (15, 20, and 27 gL-1 NaCl) on P. cruentum cell growth, biomass composition, and extracellular polysaccharides produc¬tion was investigated in this study. The results showed that the highest biomass yield and phycoerythrin content was achieved when NaCl in a concentration of 20 gL-1 was introduced into the culture medium. The measured biomass was equal to 4.3±0.1 gL-1 compared to 3.3±0.1 gL-1 for the control sample at the end of the cultivation process. The amount of chlorophyll „a“ was also 1.33 times greater in the sample with 20 gL-1 NaCl compared to the control sample with 27 gL-1, where the carotenoid content was higher. The highest amount of extracellular polysaccharide was accumulated by the microalga at 27 gL-1 NaCl. The measured viscosity was 3.35 mPa.sec - 1.4 times more than the sample with 20 gL-1 NaCl. The investigations conveyed lead to the conclusion that with only slight changes in the salt concentration, a targeted biosynthesis could be achieved, nevertheless, all other conditions remained the same. The study provides an opportunity to optimize growth and metabolite production using optimization in the cultivation process of the microalgae.