Silver nanoparticles synthesised from intracellular components of Malassezia furfur: antifungal activity against Candida auris

Objectives: Increasing resistance to conventional antifungal agents highlights the need to develop new therapeutic strategies. The green synthesis of silver nanoparticles (AgNP) using microorganisms offers a promising alternative for effective and sustainable antimicrobial agents. In this context, Malassezia furfur emerges as a viable model for the biosynthesis of AgNP with potential antifungal activity. The aim of this study was to synthesise and characterise AgNP using intracellular components of M. furfur, and to evaluate their antifungal activity against Candida auris. Methods: AgNP were synthesised from the intracellular components of M. furfur CBS 7019 according to the methodology of Murillo-Rábago et al. with modifications. The AgNP solution was characterised in terms of hydrodynamic size, polydispersity index and Z-potential by dynamic light scattering. Antifungal activity against C. auris (IMR-ML-1304) was assessed by determining the minimum inhibitory concentration (MIC) using the broth microdilution method according to CLSI M27 for yeasts. Results: The AgNP synthesis showed a colour change in solution from light yellow to dark brown, indicating the formation of the nanoparticles. The AgNP had a mean hydrodynamic size of 182 nm with a polydispersity index of 0.644, indicating a heterogeneous distribution in the sample. The surface charge of -23.5 mV indicated a moderate colloidal stability. The antifungal activity of AgNP against C. auris showed a MIC value of 32 µg/ml, highlighting its potential as an antifungal agent. Conclusions: Although there are no established breakpoints for this type of compounds, our results suggest that AgNP biosynthesis using M. furfur could be a viable alternative to obtain nanoparticles with antifungal activity against resistant strains. This approach may contribute to the development of innovative and sustainable antifungal therapies based on green nanotechnology, offering a promising avenue in the fight against infections resistant to conventional antifungals.