Innovative mycosynthesis of chitosan nanoparticles via bionanofactory Penicillium crustosum: optimization, characterization, and application against building-deteriorating fungus, Trichosporon asahii.

Biocorrosion of building materials is a global challenge that threatens both modern buildings and cultural heritage. This degradation is largely driven by interactions between microbes, particularly fungi, and various gaseous effluents containing nitrogenous, sulfurous, and carbonaceous aerosols from anthropogenic activities, leading to progressive biocorrosion of construction surfaces. Therefore, this study aims to reduce such detrimental effects using chitosan nanoparticles (CNPs). An eco-friendly biosynthesis approach was employed, using the cell-free supernatant of Penicillium sp. strain HNSAM-7 to produce the CNPs. This strain has been identified as Penicillium crustosum strain HNSAM-7 according to the analysis of ITS region sequence, together with its morphological characteristics. The physicochemical properties of CNPs were characterized; SEM and TEM analyses revealed that the biosynthesized CNPs resemble spheres, have a smooth surface, and varied in size, with an average size of 26.19 nm. The X-ray diffraction demonstrates the crystalline nature of CNPs. The FTIR analysis detected multiple functional groups involving O-H, -NH