“…Euglena gracilis, which began to appear 500 million years ago, is a species of unicellular organisms that live mostly in freshwater (Goto and Beneragama, 2010) and has no cell walls, giving it dual characteristics of plants and animals, which enable this microalga to adopt photosynthetic, heterotrophic, and mixotrophic conditions during long-term evolution (Edmunds, 1965;Zakryś et al, 2017). During this long evolution, Euglena became a highly adaptable microorganism that survived diverse and extreme conditions on the earth, such as high UV radiation, acid mine water, man-made antibiotics, heavy metal pollution, and nutrient deprivation (Ferreira et al, 2007;Moreno-Sánchez et al, 2017). Among microalgae, E. gracilis is well-known as a producer of polyunsaturated fatty acids (PUFAs) (Schwarzhans et al, 2015), vitamin E (Takeyama et al, 2015), chlorophyll a and b, several types of carotenoid pigments (Tanno et al, 2020), and polysaccharose paramylon (β-1,3-glucan) (Ivusic and Santek, 2015).…”