Effect of ultrafine CO2 bubbles on Euglena gracilis Z growth with CO2 gas bubble size and chlorophyll content.

This article investigates the effect of ultrafine carbon dioxide (CO₂) bubbles, generated using a fine ceramic nozzle, on the growth and chlorophyll content of the microalga Euglena gracilis Z under autotrophic culture conditions. The study demonstrates that feeding E. gracilis Z with fine to ultrafine bubble CO₂ (FB-CO₂), which includes bubbles smaller than 100 μm, significantly enhances cell growth and chlorophyll production compared to conventional coarse bubble CO₂ (Macro-CO₂) feeding. This improvement is attributed to the higher concentration and longer retention of non-ionized CO₂ molecules in the culture medium, facilitating more efficient passive transport of CO₂ through the pellicle membrane into the cells, thereby promoting photosynthesis. The findings suggest that ultrafine CO₂ bubble technology could offer a more efficient and cost-effective approach for industrial-scale cultivation of E. gracilis as a promising food resource and bioactive compound producer.