Enhancing biomass and lipid production in Chlorella sorokiniana via magnesium metal-organic framework of Mg-MOF-74

Background: : Metal–organic frameworks (MOFs) offer promising avenues for enhancing CO₂ biofixation in microalgae by enabling the controlled release of essential cofactors. In this study, we investigate the use of magnesium-based MOF, Mg-MOF-74, as a functional nutrient modulator to influence microalgal growth dynamics and biochemical productivity. Mg-MOF-74 is constructed from magnesium nodes and 2,5-dihydroxyterephthalic acid linkers, and decomposed during the microalgal cultivation, leading to the gradual release of both magnesium ions and linkers. Methods: : A domestic microalgal strain, Chlorella sorokiniana BSL, was cultured under varying conditions, including nitrogen sources and light intensity to determine the optimal concentration of Mg-MOF-74. The biomass yield, as well as starch, protein, and lipid contents, were assessed under controlled photobioreactor settings. Additionally, Mg-MOF-74 was characterized both before and after its application to evaluate structural changes and nutrient release profiles during cultivation. Significant findings: : Nitrogen is critical for algal culture where the highest biomass of strain BSL was achieved using urea as the nitrogen source, up to 3.36 g/L that is ra 1.3-fold improvement over ammonium. Supplementation with 50 ppm Mg-MOF-74 under 1 % CO₂ led to a 14.4 % increase in biomass and a 2.39-fold enhancement in lipid accumulation compared to untreated controls. Compared to the addition of magnesium salt or the organic linker (H₄DOBDC) alone, Mg-MOF-74 provided a more balanced and sustained release of nutrients. This controlled decomposition enhanced carbon partitioning and promoted a favorable biochemical profile. As a result, MOF-assisted nutrient delivery can fine-tune cofactor availability, improve photosynthetic efficiency, and ultimately support the production of high-value bioproducts in microalgal systems.