Abstract
Microalgae are unicellular photosynthetic organisms with considerable genetic diversity and remarkable metabolic capacity, positioning them as sustainable cellular biorefineries. They can be cultivated in open or closed systems, influenced by physical and chemical variables such as light, temperature, and nutrient availability. These conditions modulate the synthesis of valuable biomolecules, including proteins, lipids, polysaccharides, and secondary metabolites. Microalgae are especially notable for their high protein content (up to 70% w/w in Spirulina sp.), polyunsaturated fatty acids (e.g., DHA and EPA), and β-glucans with bioactive properties. Choosing the correct extraction method (mechanical, enzymatic or combined) is very important to obtain and preserve the functionality of these compounds. Despite their biotechnological potential in functional foods, pharmaceuticals, and biofuels, industrial development faces challenges such as extraction efficiency, scalability, and regulatory approval. This review compiles current knowledge on the nutritional and bioactive potential of microalgae, highlights advances in extraction technologies and discusses their potential applications in health-oriented industrial innovation.