Evaluation of carbon dioxide biosequestration capacity, biomass productivity, and biochemical composition of Gonyostomum sp. in total dissolved CO2 levels

The rise in atmospheric CO₂ due to human activities is a primary driver of global warming, demanding sustainable strategies for carbon mitigation. Among all the carbon-mitigating approaches, microalgae represent a groundbreaking solution for lowering carbon dioxide through sequestration, a recognized method for balancing CO 2 via photosynthesis. This study aimed to assess the efficiency of the native marine microalgal species Gonyostomum sp. in capturing industrial-grade CO 2 . The study was designed to culture Gonyostomum sp. at different concentrations of carbon dioxide from 55 mgL −1 (control) to 1000 mgL −1 in increments of 200 mgL −1 , all while maintaining 25° ∁ temperatures and illumination was provided at a constant intensity of 150 μEm −2 s −1 , with a 24-h light regimen to facilitate continuous photosynthesis and optimal cell growth. Growth parameters, including biomass productivity and specific growth rate, were measured alongside biochemical analyses of the biomass, such as proximate compositions (protein, lipid, and carbohydrate content), fatty acid profiles, and chlorophyll content. The maximum carbon fixation rate was found to be 2.04 ± 0.13 gL −1 day −1 at 400 mgL −1 dissolved CO 2. Gonyostomum sp. exhibited variation in carbon content, sequestration rate, and biomass productivity rate of up to 1000 mgL −1 from control of total dissolved carbon dioxide in the cultivation media. Whereas 800 mgL −1 dissolved carbon dioxide was optimum for maximum protein and carbohydrate content (38.76 ± 8.45% and 17.14 ± 0.64%), and the highest lipid content (53.76 ± 2.29%) was found at 600 mg/L dissolved carbon dioxide. Dissolved carbon dioxide in the cultivation conditions was favorable for saturated fatty acid composition (C 8 C 24 ). A significant amount of polyunsaturated fatty acids ranges from 25.03 ± 0.2% to 36.02 ± 0.12%, also found with dissolved carbon dioxide treatment. Therefore, the findings of the study conclude that Gonyostomum sp. will be a competent species for carbon dioxide removal, nutrition supply, and SAFA and UFA production. • Pure industrial grade carbon dioxide grade carbon dioxide gas was used to determine the sequestration capacity of Gonyostomum sp. • Gonyostomum sp. was identified as a high-dissolved‑carbon-tolerant species. • More than half (53.76 ± 2.29%) of the nutrition of Gonyostomum sp. was total lipid percentage with 600 mgL −1 carbon dioxide supply.