Light Emitting Diode (LED) Illumination For Enhanced Growth And Cellular Composition In Three Microalgae

Abstract

Light wavelength is an essential parameter of microalgal growth and light spectrum quality affects the algal metabolism. Light-emitting diodes (LEDs) emit a very narrow wavelength which addresses fundamental as well as applied aspects of light color on biomass and value-added compound formation in microalgae. In this study, Arthospira platensis, Chlorella vulgaris and Scenedesmus obliquus were cultivated in Bold’s basal medium under five different LED illuminations (white, blue, green, yellow and red) to augment growth, pigment, protein, carbohydrates and lipid production. Dry weight of microalgae at the end of 10 days cultivation period revealed that higher content under the LED illumination was in the order of red>white>blue. Highest Chlorophyll a content of 8.4 mg g-1 was recorded in C. vulgaris under red LED. Whereas green LED illumination has resulted higher content of Chlorophyll b with 2.0, 1.98 and 1.68 mg g-1 in A. platensis, C. vulgaris and S. obliquus respectively. Similarly highest carotenoid content of 6.1 mg g-1 in A. platensis was recorded in green LED. Total carbohydrates of microalgae were increased under blue light and the maximum content of 52.1 mg g-1 was found in C. vulgaris. Protein content in the range of 102.7-97.5 mg g-1, 77.9-76.5 mg g-1 and 51.9-49.4 mg g-1 was observed in A. platensis, C. vulgaris and S. obliquus under blue and green LED. Lipid content of 5.68 % and 4.96 % was obtained in C. vulgaris and S. obliquus under blue LED. This was followed by 4.37% and 3.86% under red LED illumination for the same species. Based on the results, selection of blue and red LED illumination to enhance microalgal growth and cellular composition is possible in the selected microalgae.