Amyloid fibrils of the Als5p-derived peptide NH₂-SNGIVIVATTRTV-COOH influence the biofilm formation of Candida albicans by shape-edging microcolony morphology

Candida species are major contributors to nosocomial infections, with biofilm formation being a critical virulence factor that enables persistence in clinical settings and resistance to antifungal therapies. Central to biofilm development is the adhesion of fungal cells, a process mediated by surface proteins such as Als5p in Candida albicans. The amyloid-forming peptide sequence within Als5p (322SNGIVIVATTRTV334) has been implicated in mediating adhesion and biofilm formation; however, its role in shaping the biofilm architecture has not been fully elucidated. In this study, we demonstrated that the addition of Als5pFP promoted biomass accumulation in C. albicans biofilms under laboratory conditions, including complex media and at temperatures compatible with clinical biofilm assays. Using advanced image analysis of microscopy images, we show that the Als5p peptide induces a distinct morphological effect on biofilms: a shape-edging of microcolony structures, characterized by the concentration of fungal cells into denser aggregates and the reduction of cells in intermediate spaces. These observations suggest a potential role of amyloid-like fibrils formed by the Als5p peptide in influencing the spatial organization of C. albicans biofilms. This discovery presents a novel aspect on how these fibrils affect the biofilm architecture extending beyond previous studies, which primarily focused on biomass accumulation. Our findings contribute to the understanding of the architectural development of C. albicans biofilms and provide a foundation for future research aimed at targeting the amyloid structures within fungal biofilms. Furthermore, the results may support the design of biofilm-targeting antifungal agents and development of biosensors for monitoring amyloid formation during infection.