Effects of Light Regime on Extracellular Polysaccharide Production by Porphyridium Cruentum Cultured in Flat Plate Photobioreactors

Light quality was a key factor for controlling the growth and polysaccharide production of microalgae. Growth and extracellular polysaccharide production by Porphyridium cruentum cultured in flat plate bioreactors were measured as a function of light wavelength and intensity. The growth rate and polysaccharide production of Porphyridium cruentum increased with enhanced of light intensity, however a light level beyond the saturation point inhibited the growth of microalgae. Here, Photon flux density of 80 mu E m^-2 s^-1 was the optimal light level for maximum biomass and polysaccharide production by Porphyridium cruentum. Continuous light radiation enhanced the growth rate, but the maximum polysaccharide production was obtained at the light-dark cycle of 18:6. It was found no significant difference in cell growth between different spectrums. Green light, natural light and yellow light were found more suitable for increasing polysaccharide production than blue light and red light.