Designing Amyloid-Like Protein Aggregates from Microalgal Biomass

Our societal dependence on petrochemical-derived plastics has significant environmental ramifications, with about 80% of such plastics ending up as persistent waste. To this end, we investigate the extraction and purification of proteins from microalgae, specifically spirulina and chlorella, and their self-assembly into amyloid-like aggregates as building blocks toward the development of sustainable bioplastic materials. After self-assembly, spirulina proteins formed beta-sheet-rich structures with a typical (albeit short and worm-like) fibrillar morphology, while chlorella proteins predominantly aggregated into nonfibrillar, spherical/annular structures. Despite their morphological differences, both microalgal protein aggregates exhibited impressive stability across a wide pH range, persisting up to pH 11 before disaggregating at pH 12. In short, this work highlights the importance of biomass source, protein purity, and composition on the aggregation process of differing proteins. Given the high protein content and expanding industrial production of microalgae, spirulina and chlorella present an untapped resource for the development of sustainable bioplastics.