Assessment of the optimum growth medium and the effect of different light intensities on growth and photosynthetic pigments of Chlorella vulgaris and Scenedesmus arvernensis

Abstract

CHLORELLA vulgaris and Scenedesmus arvernensis are common eukaryotic green microalgae that have a very wide use in various applications. They can be used as raw materials in bio-energy production, in aquaculture nutrition, in pharmaceuticals, cosmetics, biofertilizers, biodegradation of wastes and dyes. So, this required several studies to test some factors that can influence the growth rate and evaluate their yield. This study investigated the effects of different media compositions: Bold’s basal medium, BG-11 medium, modified Chu-10 medium, and Kuhl’s medium on growth of C. vulgaris and S. arvernensis. Then, study the effect of four different light intensities on the growth rate using the optimized medium. The growth was recorded by estimating optical density (OD), cell counting (CC) and total chlorophyll contents. The results showed that the maximum growth was recorded at Modified CHU’s 10 medium for C. vulgaris and BG-11 medium for S. arvernensis. The growth was compared with the initial record of C. vulgaris and S. arvernensis inocula; the OD increased by 6.85 and 5.15 times, respectively. C. vulgaris showed the optimum CC 9.60 times and total chlorophyll 7.96 times. CC recorded 10.42 times and total chlorophyll increased 5.90 times for S. arvernensis. Light intensities experiment showed that C. vulgaris gave the best growth rate at 60 μmol photons m-2s-1, on the 35th day of cultivation with increasing in OD, CC and total chlorophyll, (6.18, 5.27 and 3.58 times), of the initial record, respectively. Concerning S. arvernensis optimum growth rate was reached at 40μmol photons m-2s-1, on the 35th day accompanied by an increment in OD, CC and total chlorophyll, (6.20, 4.55 and 10.04 times), of the initial record, respectively.