Evaluation of Growth Performance and Nutritional Profile of Selected Marine Microalgae Cultured in Low-Cost Media

Abstract

Microalgae are emerging as a sustainable and versatile resource for aquaculture, biofuel, and nutraceutical industries. This study investigates the growth performance and nutritional profile of the marine microalga Gonyostomum sp. when cultured in costeffective media formulated with NPK fertilizer, compared to conventional Conway medium. The microalga was cultivated in varying NPK concentrations (7 mg, 9 mg, 11 mg, and 13 mg/L), with Conway serving as the control. Growth parameters, biomass yield, and biochemical composition (protein, lipid, and carbohydrate contents) were analyzed to evaluate media efficacy. The 11 mg/L NPK treatment (G11) supported the highest cell density among the NPK treatments (7.975 × 10⁶ cells/mL), while Conway medium exhibited the overall highest growth and nutritional content. Notably, G11 yielded a slightly higher lipid content (29.5%) than Conway (27.4%), indicating its potential for lipid-rich applications such as biofuel. However, Conway medium significantly outperformed NPK in protein and carbohydrate accumulation. Economically, NPK media were substantially more cost-effective, suggesting promise for scalable microalgae cultivation in resource-limited settings. The study highlights the viability of NPK-based media for mass cultivation of microalgae, particularly when supplemented with essential trace nutrients, offering a practical approach to enhance sustainable aquaculture and contribute to Bangladesh's blue economy.