Screening of chitosan against wood-deteriorating fungi

Chitosan, a derivative of the natural amino polysaccharide chitin, has proven effective as a potential environmentally benign antimicrobial component. Few studies have focused on chitosan applied to wood against wood-inhabiting and decaying fungi. In these screening studies several mycological experiments were performed to screen chitosan as a potential wood-protecting agent. Growth studies on chitosan-amended media showed total inhibition of Poria placenta, Coriolus versicolor and Aspergillus niger using 1% w/v concentration. Chitosan with high average molecular weight (MW) was more efficient against mould and staining fungi than chitosan with low MW. Agar plate leaching tests showed only a small leaching effect using a 5% concentration on A. niger and P. placenta. Decay testing with P. placenta demonstrated efficacy using 5% and 2.5% concentrations in unleached samples. Leaching decreased the efficacy of chitosan and further investigations are needed to improve the fixation in wood.