Immobilized Euglena Cells (Euglena Beads) are Useful for Laboratory Exercises on Photosynthesis at the Secondary Level

抄録

Euglena is a common photosynthetic protist, useful as teaching material in biology at secondary and tertiary levels, because it has some unique features of interest to students. Euglena can be cultured in an inorganic medium (HYPONEX solution) without contamination by heterotrophic microorganisms, rendering it suitable for experiments on photosynthesis. In this study, we immobilized Euglena cells in calcium alginate gel beads (“Euglena beads”), facilitating their repeated use in experiments on photosynthesis. In this immobilized state, Euglena could propagate could reproduce in 0.1% HYPONEX solution and gradually turned green under the culture conditions. The Euglena beads were demonstrated to be a useful substitute for aquatic plants, such as Elodea and Cabomba, in the qualitative experiments in which a pH indicator was used to detect photosynthetic CO₂ consumption. Euglena beads cultured for 30 days had sufficient photosynthetic activity to allow measurement of photosynthetic rates within 30 minutes.