Chitosan, a polymer of D-glucosamine, is known for its antimicrobial activity. However, the physicochemical properties of chitosan depend upon three principal factors, i.e. source of raw material, molecular weight and degree of deacetylation. Here, we report synthesis and characterization of chitosan oligomers prepared by deaminative depolymerization of chitosan (s) obtained from Sigma Aldrich and China (industrial grade). Subsequently their antifungal activies were evaluated using both agar nutrient medium and wood decay bioassays. The nutrient medium bioassay results showed that chitosan(s) and chitosan oligomers affected mycelial growth to different magnitudes. Nevertheless, two of the low-MW chitosan oligomers completely inhibited the growth of all the tested fungi as compared to high-MW chitosan oligomers. However, the work presented in this paper, depicts that antifungal activity increases by decreasing the degree of polymerization of chitosan oligomers, which is a contrary to the reported literature. The wood decay trial confirmed the antifungal activity of chitosan oligmers against basidiomycetes but highlighted the leachability of chitosan when exposed to water.

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