Carbon-13 CP/MAS solid state NMR and X-ray diffraction spectroscopy studies on lime wood decayed by Chaetomium globosum

Abstract

The degradation of the plant cell wall by microorganisms has been studied by X-ray diffraction, and solid state CP/MAS 13C NMR spectroscopy. Lime wood ( Tilia cordata Miller) samples were inoculated with Chaetomium globosum for various durations up to 133 days. Structural modifications were assessed by comparing decayed lime wood samples with reference. These methods proved to be able to give insights into the modifications at a molecular level of the cell wall components by Ascomycetes fungi attack. Significant changes in relative crystallinity and apparent lateral crystallite size, as measured by XRD, were detectable relatively early in the decay process. The content of hemicelluloses and cellulose in the wood samples decreased after biodegradation with Chaetomium globosum. The main chemical changes in wood during decay are the loss of hemicelluloses and cellulose simultaneously with lesser changes in lignin structure, which mainly consist in partial loss of methoxyl groups and Cα–Cβ bond cleavage and loss of β-O-4 linkages.