ERGOSTEROL PRODUCTION IN ALGAE Chlorella sorokinana AND STUDY THE EFFECT OF SODIUM CHLORIDE AND GROWTH PHASES ON PHOTOSYNTHETIC PIGMENTS

The present study aimed to detect the production of Ergosterol in Chlorella sorokinana and the effect of sodium chloride (NaCl), and the difference of growth phases on the production of the compound and photosynthetic pigments. The results showed that there is a positive effect on increasing the production of the Ergosterol compound. Its maximum value was 48.591 mg. L^-1 at the concentration of 300 ppm. Concerning the difference in growth phases, the second growth phase was the best in obtaining the maximum value of Ergosterol, which was 44. 941 mg. L^-1. Also, the results of the interaction between the concentrations of NaCl and the difference in the growth phases indicated that the highest value was 50.493 mg. L^-1 at the concentration of 300 ppm at the second growth phase. In contrast, there was a negative effect of NaCl on photosynthetic pigments; the highest values of chlorophyll a and b and total chlorophyll were 0.04, 0.07, and 0.13, respectively, at the control treatment, whereas these values gradually decreased with the increase of NaCl concentration to reach the lowest values; these were 0.01, 0.04 and 0.06 mg. L^-1 respectively at the concentration of 300 ppm. The results of the different dates of cell harvesting showed that the highest values for obtaining an increase in the concentration of chlorophyll a and b pigments and total chlorophyll were at phases 1; they were 0.06, 0.09, and 0.17 mg. L^-1 respectively. Accordingly, we concluded that the salt stress from NaCl had a positive effect on increasing the concentration of Ergosterol, which is one of the antioxidant steroidal compounds. On the other hand, it had a negative effect on the photosynthetic pigments.