Effect of salinity and pH on the biochemical composition of the microalgae Scenedesmus sp. in batch cultures

Abstract

The present study evaluated the effect of pH (5, 6, 9, 11) and salinity (6, 12, 26 and 36 UPS) on the growth and production of pigments, proteins, carbohydrates and lipids of the microalga Scenedesmus sp., discontinuous cultures were maintained with constant aeration, irradiance of 50.22 μmol m-2s -1, photoperiod 12:12 h and 25 ± 2 ºC. The results indicated that in non-saline cultures and at pH 9 the highest cell densities were presented with 9.48 ± 0.32x106 cells.mL-1. Meanwhile, chlorophyll a and b were produced at 0UPS and pH (8-10) with 5.52 ± 0.09 and 2.03 ± 0.16 μg.mL-1, respectively, but with a decrease with the increase in NaCl. Likewise, carotenoids were increased to 12UPS and pH 11 from 0.20 ± 0.004 to 1.45 ± 0.004 μg.mL-1 and the highest in lipids (p <0.05) was evident at 6UPS with 16 ± 32.37 μg.mL -1. However, the highest protein and carbohydrate contents were produced at 0UPS and pH 11 with 377.37 ± 23.88 and 122.69 ± 1.68 μg.mL-1; respectively. The results of the gradual adaptation to NaCl allow us to conclude that this strain of Scenedesmus sp., Although it is halotolerant, showed an optimal growth, a higher content of chlorophyll and of carotenoids in non-saline conditions and in an alkaline medium.