Researchers from Yangzhou University have shown how a combination of monochromatic red and blue light emitting diode (LED) illumination on one type of microalga could increase growth of biosynthesis for the development of biofuel.
The research focused on Dunaliella salina (D.salina), a microalga extracted from sea salt fields and found in salt lakes. The algae is known for its pink color and high levels of carotenoid, which is widely used in foods and cosmetics.
Microalgae tend to accumulate higher amounts of lipids than other biomass feedstocks do, meaning it could be turned into usable biofuel. Because the D.salina algae lacks a cell wall, it could make algae biofuel production easier to pursue.
LEDs can optimize plant growth, particularly in greenhouse cultivation. All parts of the visible spectrum are used in photosynthesis, but light also influences plant development. Adding more blue or red light affects different plants in different ways.
In the Yangzhou study, researchers applied red, blue or a combination of the two to illuminate the D.salina culture and found that different intensities of blue light did not significantly affect microalgae growth but boosted the lipid, protein and carbohydrate levels. Red light, meanwhile, reduced algae growth and lipid formation, compared to blue or white light.
When applied in various ratios, the microalgae showed a boost in growth and lipid productivity. The optimal 4:3 ratio of red and blue light improved lipid productivity by more than 35% and increased dry biomass yield by more than 10% compared to just white light control.
The next steps are to analyze the composition of the fatty acids synthesized in the algae under the combined light conditions that increased lipid production.
"Biodiesel performance is dependent on the composition of fatty acids, so we want to determine how the combined monochromatic lights would affect the quality of microalgae biodiesel," said Xiaojian Zhou, researcher at Yangzhou University.
The full research can be found in the Journal of Renewable and Sustainable Energy.
