Optimizing <i>Chlorella vulgaris</i> cultivation under nutrient stress using the Taguchi method and desirability analysis

Abstract Climate change has intensified research on carbon fixation, as fossil fuels remain the primary source of greenhouse gas emissions. Biofuels have emerged as a promising alternative, and biorefineries are essential for sustainable technologies. This study examines the potential of Chlorella vulgaris for integrated bioethanol and biodiesel production, focusing on the effects of culture medium and nutritional stress on metabolism. A systematic experimental design using a Taguchi L8 orthogonal array evaluated three factors at two levels: culture medium (Detmer’s Medium, DM, and Bold Basal Medium, BBM), nitrogen concentration (360–600 mg L −1 ), and phosphorus concentration (120–360 mg L −1 ). Responses were measured as biomass productivity, reducing sugars (bioethanol precursor), and lipids (biodiesel precursor). Reducing sugars were quantified by acid hydrolysis followed by spectrophotometric analysis with 3,5‐dinitrosalicylic acid, and lipids were extracted using chloroform–methanol (2:1). The BBM medium gave stable results, with higher biomass and lipid productivity under elevated nutrient concentrations. Detmer’s Medium exhibited greater variability, enabling the accumulation of lipids and reducing sugars, depending on nutrient levels. Desirability analysis identified DM medium with 600 mg L −1 nitrogen and 360 mg L −1 phosphorus as the optimal conditions for maximizing biomass, reducing sugar, and lipid yields, indicating that C. vulgaris experienced greater metabolic stress in DM, a medium still scarcely explored in the literature. Statistical analysis confirmed interaction effects between culture medium and nutrient concentration. These findings demonstrate the effectiveness of combining experimental design with desirability analysis and support using high nutrient stress in DM as a strategic approach for producing biofuel precursors.