Adaptation of Graesiella emersonii Strains to Atmospheric and Enriched CO2: Exploring Growth and Photosynthetic Efficiency

: Graesiella emersonii, an aeroterrestrial green microalga, exhibits high adaptability to extreme environmental conditions, making it of interest for biotechnological applications. Investigating photosynthetic performance is essential to select high-yield strains and optimize the sustainable production of biomass and bio-products. In this study, two strains (053 and 054) were cultured under atmospheric (0.04%) and elevated (2%) CO2 conditions to analyze growth, pigment content, and photosynthesis. Strain 053 showed superior photosynthetic performance and productivity under atmospheric conditions, whereas 2% CO2 enhanced growth in both strains, with a significant increase in photosynthetic efficiency in strain 054. The observed differences highlight strain-specific adaptations to CO2 availability and suggest the potential of each strain depending on the cultivation environment.