Effect of ultrafine CO2 bubbles on <i>Euglena gracilis Z</i> growth with CO2 gas bubble size and chlorophyll content

Microalgae have been explored as a viable alternative food source. Among them, Euglena gracilis stands out as a promising single-cell algae. However, the challenge lies in developing more efficient and cost-effective methods for industrial mass production of E. gracilis under controlled culture conditions. Our research aimed to address this by investigating the role of nanotechnology in using fine to ultra-fine bubble CO2 (FB-CO2)-ranging from micrometer to nanometer size-as feeding material to promote cell harvest of E. gracilis Z in autotrophic culture conditions. Our findings suggest that feeding E. gracilis Z with FB-CO2 increased cell growth and chlorophyll content in autotrophic culture conditions. The promotion effect can be attributed to the provision of non-ionized carbon dioxide to the photosynthetic system, which was further enhanced by the dispersion of FB-CO2 in the culture media under acidic conditions.