Kayla McKinley, Gulnihal Ozbay
Microalgae are increasingly recognized as versatile biological platforms capable of supporting sustainable food, energy, environmental, and industrial systems. This review critically evaluates recent advances in microalgal biotechnology, with a focus on applications in which biological performance, resource recovery, and scalability intersect. Emphasis is placed on microalgal biomass composition, including proteins, lipids, polyunsaturated fatty acids, pigments, and polysaccharides, and how these components underpin applications in food, feed, biofuels, bioremediation, and bioproduct development. Environmental applications, particularly wastewater treatment and carbon capture, are examined as integrated systems that couple nutrient removal with biomass valorization. Advances in strain improvement, including genetic engineering and multi-omics approaches, are discussed alongside persistent limitations related to species-specific transformability, production costs, and downstream processing. Rather than providing an exhaustive survey, this review highlights cross-sectoral trends, quantitative performance metrics, and technological bottlenecks that constrain commercialization. By comparing biological potential with engineering and economic realities, this work identifies priority research directions needed to advance microalgae-based systems within circular bioeconomy frameworks. • Microalgae provide proteins, lipids, pigments, and bioactives for food and feed systems. • Microalgal platforms enable nutrient recovery, carbon capture, and wastewater treatment. • Advances in genetics and omics improve strain performance and metabolite yields. • Integrated biorefineries improve the economic feasibility of microalgal biomass use.