Effect of Light Wavelengths on Biomass Production and Pigment Enhancement of Chlorella vulgaris in Indoor System

Fresh water microalgae, Chlorella vulgaris, is commonly used as a food type for live feed production because of smaller size and high pigment content. The key to economic production of microalgae is to optimize lighting conditions, photoperiod and wavelength of light for efficient photosynthesis. In the investigation, C. vulgaris was grown for six days in a cylindrical FRP (Fibre Reinforced Plastic) tanks (500L) with under water light facility using acrylic pipes and LEDs (Light Emitting Diodes) at 5 klux green light (495–570 nm), red light (620–750 nm), blue light (450–495 nm) and white light (380 to 750 nm). The results showed that the highest biomass (6.50±154.21×107 cells mL-1) was observed in culture illuminated with green light at ambient temperature but having lesser cell size (2.7-5.8 µ). The biomass observed in culture illuminated with red, blue and white colour was 4.34±257.25×107 cells mL-1, 5.54±287.74×107 cells mL-1 and 5.10 ± 380.45×107 cells mL-1 respectively while cell size observed was 5.2- 9.4 µ, 5.1-6.8 µ and 5.0-8.9 µ. The highest amounts of chlorophyll a (0.141±0.17 mg mL-1) and chlorophyll b (0.177±0.13 mg mL-1) were observed in cultures illuminated with green light while the highest amount of astaxanthine (0.0126±0.35 mg mL-1) was observed in cultures illuminated with red light. To conclude, C. vulgaris can be produced in mass using green light illumination efficiently while astaxaathin content can be increased using red light illumination.