Insights into the fungal secretomes and their roles in the formation and stabilization of the biogenic silver nanoparticles†

Abstract

The biosynthesis of silver nanoparticles (AgNPs) using biological systems has emerged as a promising alternative to traditional chemical methods, providing eco-friendly solutions in nanotechnology. This study investigates the secretomes of two strains of Fusarium oxysporum (VR039 and 07SD) to synthesize AgNPs (AgNP@Fo VR039 and AgNP@Fo 07SD), characterized by similar sizes of 35.4 ± 12.4 nm and 28.6 ± 9.5 nm, respectively. We conducted proteomic analysis via mass spectrometry on both secretomes and nanoparticles, identifying proteins involved in the biosynthesis, stabilization, and antimicrobial activity of the nanoparticles. Our results indicate notable similarities in the proteomes of both nanoparticles and their respective secretomes, correlating with similar antimicrobial efficacy against Staphylococcus aureus and Escherichia coli, as demonstrated through bacterial growth inhibition assays. The presence of redox proteins, such as glyceraldehyde reductase and FAD-oxidoreductase, suggests a potential mechanism for the generation of reactive oxygen species (ROS) and oxidative stress in bacterial cells, further validated by fluorescence microscopy to differentiate viable from non-viable cells. Unlike previous studies that have focused separately on metal ion reduction or nanoparticle stabilization, our findings reveal a coordinated biosynthetic process where the same proteins mediate both functions. This overlap between the secretome and nanoparticle proteome provides new insights into fungal-mediated nanoparticle synthesis, highlighting the multifunctionality of fungal proteins in bionanotechnology. By demonstrating how secreted enzymes directly contribute to nanoparticle formation, this study paves the way for more efficient, scalable, and environmentally sustainable approaches to biogenic nanoparticle production.