Examination of the Quantum Yield of Euglena, a Photosynthetic Green Algae

Abstract

We are planning to develop a new food production system using Euglena, a photosynthetic microalgae, replacing higher plants to feed the rapidly increasing global population. In this study, we evaluated the quantum yield of Euglena and proved that Euglena is a more effective food source than higher plants. Euglena was cultured under three light conditions of red and blue light emitting diodes (LEDs) and white fluorescent lamps, aerated with the addition of 0.04 and 10% CO₂, respectively. We measured cell numbers, dry weight, and carbon concentration everyday. The quantum yield (QY) was calculated at the log phase. QY=the quantity of energy for carbon fixation/photon energy. As a result, we found that the optimal light conditions of the white fluorescent lamp for the quantum yield of CO₂ fixation was 30 μmol m^-2 s^-1, aerated with the addition of 10% CO₂. We found that the optimal light conditions of LEDs were 30 μmol m^-2 s^-1, aerated with the addition of 10% CO₂, as well as a red:blue photon ratio of 9:1. The QY of Euglena under LED light conditions reached 14%, higher than that of higher plants (under 11%, theoretically). We concluded that the quantum yield of Euglena was greater than that of higher plants. We will further investigate other basic data of Euglena as a food production system.