Bioprocess Design and Optimization for Pharmaceutical Production Using Microalgae and Cyanobacteria

Microalgae and cyanobacteria have emerged as platforms for producing recombinant biologics, vaccine antigens, and bioactive compounds of pharmaceutical interest. However, their translation beyond proof-of-concept remains limited by light-field heterogeneity, gas–liquid mass-transfer constraints, product instability, and matrix complexity, all of which affect recovery, selectivity, and batch comparability. This review synthesizes and organizes published evidence using a process-engineering framework organized around product class, product localization, upstream–downstream coupling, and photobioreactor scale-up. It further considers the role of Quality by Design (QbD), model-informed development, techno-economic assessment (TEA), and life cycle assessment (LCA) in route selection and quality-oriented process development. Across the reported routes, the dominant burden shifts from disruption and clarification in intracellular products to extracellular stability and time-to-capture in secreted products, whereas biomass-based formulations are governed by potency and stabilization consistency, and analog-rich metabolites by profile control and selective fractionation. Current limitations include the scarcity of models that incorporate quality attributes as explicit outputs, the incomplete representation of regulated manufacturing burdens in TEA and LCA, and the lack of minimal, reproducible analytical panels adapted to product class and matrix. By framing these organisms as pharmaceutical process platforms rather than as hosts assessed only by titer, this review provides an engineering basis for scale-up, route prioritization, and controllable manufacturing.