Scoping Antifungal Activities of Various Forms of Chitosan Oligomers and Their Potential Fixation in Wood

Chitosan oligomers （average Dp-4） are known for their antifungal activity and wood decay resistance. These oligomers are susceptible to moisture, and promote yeast growth upon air exposure after a sufficient length of time. Chitosan oligomers of three different states viz. completely dried, freshly prepared and highly viscous form, were prepared to compare their in-vitro antifungal activities against three brown-rot fungi, two sapstain and one mould fungus using agar nutrient medium. Additionally, a mixture of chitosan oligomers and boric acid was used for wood treatment. The nutrient medium bioassay results show that all states of chitosan oligomers inhibited the growth of tested basidiomycetes fungi, but not sapstain and mould fungi. Subsequently, wood decay results confirm antifungal activity of chitosan oligomers plus boron against basidiomycetes, but highlighted their leachability upon water exposure.