Learning Light Scattering From Algae

Through tiny structures known as coccoliths, microscopic algae are able to control light scattering, possibly influencing solar light exposure in the ocean.

AsianScientist (Sep. 22, 2015) – Researchers at Hiroshima University and the University of Tsukuba have shown that coccolith disks made of calcium carbonate in the algae Emiliania huxleyi potentially perform roles in reducing and enhancing the light that enters the cell by light scattering. Their findings, published in Scientific Reports, could help promote efficient bioenergy production using microalgae.

Finding a renewable source of energy is perhaps one of the most important problems on earth. Recently, many types of renewable energy resources such as solar light, wind, water, and biomass have attracted attention for their use as alternative energy sources apart from fossil fuel.

Coccoliths are disk-shaped plates of calcium carbonate formed by coccolithophores, which are single-celled algae such as E. huxleyi. The most important question concerning coccolith function is with regard to how they modulate solar light in the ocean, where huge blooms of E. huxleyi have frequently been observed as satellite images by SeaWiFS Color Senor from space. Recently, studies that focus on the optical function of coccoliths have been reported. In these studies, the light scattering of randomly oriented coccoliths was measured.

Professor Masakazu Iwasaka at Hiroshima University and Professor Yoshihiro Shiraiwa at the University of Tsukuba prepared an aqueous suspension of isolated coccoliths of E. huxleyi cells and examined their light-scattering properties. They found that the coccoliths showed magnetic orientation when floating in water, and the light scattering was changed by the magnetically-oriented coccoliths.

“Surprisingly, the percentage of coccoliths oriented in the same direction increased during exposure to the 400 mT to 500 mT magnetic field. In addition, an individual coccolith has a specific direction of light-scattering,” Iwasaka explained.

These results can contribute to the understanding of how coccoliths control light and utilize optical energy for the photosynthesis in E. huxleyi. Furthermore, since no artificial method to reproduce precise structures such as a coccolith without a coccolithophore exists so far, these coccoliths can be used as novel micro/nano optical devices owing to their ability to modify light.

The article can be found at: Mizukawa et al. (2015) Light Intensity Modulation by Coccoliths of Emiliania huxleyi as a Micro-Photo-Regulator.


Source: Hiroshima University.
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