Isolation and Characterization of Chitosans from Different Fungi with Special Emphasis on Zygomycetous Dimorphic Fungus : Evaluation of Its Chitosan Nanoparticles for the Inhibition of Human Pathogenic Fungi.

The cell wall chitosan was extracted from fungi belonging to different taxonomic classes, namely, (Zygomycetes, dimorphic), , , , and (Ascomycetes, yeasts), and and (Basidiomycetes). The maximum yield of chitosan was 60.89 ± 2.30 mg/g of dry mycelial biomass of . The degree of deacetylation (DDA) of chitosan extracted from different fungi, as observed with H NMR, was in the range of 70-93%. chitosan exhibited the highest DDA (92.78%). The characteristic absorption bands were observed at 3450, 1650, 1420, 1320, and 1035 cm by FTIR. Compared to chitosan from marine sources (molecular weight, MW, 585 kDa), fungal chitosans showed lower MW (6.21-46.33 kDa). Further, to improve the efficacy of chitosan (Bp), nanoparticles (Np) were synthesized using the ionic gelation method and characterized by dynamic light scattering (DLS). For yeast and hyphal chitosan nanoparticles (BpYCNp and BpHCNp), the average particle size was <200 nm with polydispersity index of 0.341 ± 0.03 and 0.388 ± 0.002, respectively, and the zeta potential values were 21.64 ± 0.34 and 24.48 ± 1.58 mV, respectively. The chitosans and their nanoparticles were further evaluated for antifungal activity against human pathogenic ATCC 10231, NCYC 388, ATCC 750, ATCC 34664, and ATCC 10578. BpHCNps showed lower MIC values (0.025-0.4 mg/mL) than the chitosan polymer against the tested human pathogens. The study suggested that nanoformulation of fungal chitosan, which has low molecular weight and high % DDA, is desirable for antifungal applications against human pathogens. Moreover, chitosans as well as their nanoparticles were found to be hemocompatible and are therefore safe for healthcare applications.