Effect of Light Intensity and pH on Cell Density Assessed by Spectrophotometry for the Unicellular Algae Chlorella vulgaris

Abstract

In this study, an effective environment for Chlorella vulgaris growth is sought after. As a substitute source of food and feed, increasing the cell density of Chlorella culture is one of the keys to ensuring sustainability. It can be showed from different studies that optimum light intensity and pH could increase cell density. In this study, the effects of light and pH on the growth rate of C. vul-garis were observed in photobioreactor. A specific wavelength (682 nm) was determined by UV-Vis Spectrophotometry to carry out the further analysis. The light intensities were set at 7409, 9261 and 11,113 lux; pH values were set at 7, 8 and 9 respectively. The experimental results depicted the light intensity of 9261 lux as the best due to the higher number of cells (48.56 × 10 6 cells/mL) obtained using this intensity. In terms of pH, without pH control, cell numbers were found to be highest under the light intensity of 9261 lux. When pH was controlled, it was found that under the optimum light intensity, pH control between 7.0 and 7.5 was the optimum range for the growth of C. vulgaris. Moreover, this method of study may possibly be a promising source of low cost culture for Chlorella vulgaris.