Unlocking the Potential of Macroalgae: Innovative Pretreatment Strategies for Efficient Biorefinery

Macroalgae represent a promising third-generation feedstock for biorefinery due to their high biomass productivity and non-reliance on arable land. However, their complex cell wall structure poses a significant barrier to efficient bioconversion. This review integrates current pretreatment methods, including physical, chemical, biological, and combined approaches, with a focus on their mechanisms, effectiveness, and limitations. Furthermore, it explores the conversion of pretreated macroalgal biomass into bioenergy and biochemicals, such as bioethanol, organic acid and polyhydroxyalkanoate, via microbial fermentation. The review also examines the application of genetic editing tools (e.g., CRISPR-Cas systems) for the targeted modification of macroalgae to improve their inherent characteristics for biorefinery, such as reducing biomass recalcitrance or increasing the content of target carbohydrates. Finally, future perspectives on technological innovations and integrated industrial chains of macroalgal biorefinery are discussed. This review serves as a systematic reference for deepening the understanding of macroalgal cell wall deconstruction processes and supports the development of efficient and environmentally benign pretreatment strategies to advance macroalgal biorefinery toward industrialization.