Effects of light-emitting diodes (LEDs) on lipid production of the aerial microalga Coccomyxa sp. KGU-D001 under liquid- and aerial-phase conditions.

Algal biofuels are a promising alternative to fossil fuels, but their widespread use is hindered by problems with mass production. Light-emitting diodes (LEDs) with specific light wavelengths could be used as an energy source for algal growth and lipid synthesis. In this study, the effects of light source on the biomass and lipid production of the aerial microalga Coccomyxa sp. KGU-D001 were evaluated using LEDs. The integration of two-phase cultures, including growth and lipid production under the stress of nitrate depletion, was assessed for efficient lipid production under liquid- or aerial-phase conditions. Different wavelengths of light (blue, green, and red) were tested under liquid- and aerial-phase conditions. Under aerial-phase culture, the fatty acid contents in biofilm reached 320 mg g DWC with the red LEDs. In view of these findings, we describe a one-step culture method for growth and lipid accumulation in algal biofilm under aerial-phase culture with red LED irradiation. When Coccomyxa biofilm was cultured on wet cotton wool with BBM in a petri dish under the red LED, it was able to grow and accumulate lipids under the aerial-phase condition. Based on the results of this study, a potential method for a continuous biodiesel production system is proposed.