CPMAS carbon-13 NMR study of lignin preparations from wheat straw transformed by five lignocellulose-degrading fungi

Abstract

After solid-state fermentation of wheat straw with five lignocellulose-degrading fungi, lignin was extracted and studied by CPMAS 13C NMR. The increase in the intensity of the signals in the 200-164 ppm range is evidence for the oxidative alteration of lignin. The lignins degraded by the white-rot fungi Ganoderma australe and Phanerochaete chrysosporium showed a decrease in the amounts of aryl carbons, whereas the intensity of the 33 ppm signal from saturated alkyl structures was strongly increased by the latter fungus. The cellulolytic Chaetomium uirescens and Trichoderma Zongibrachiatum and the ligninolytic Fomes fomentarius caused the selective decrease of some signals assigned to lignin-carbohydrate complexes. A low molecular weight fraction was recovered by adsorption on poly(vinylpyrrolidone). The C=O signals of this fraction were strongly increased by the ligninolytic species, whereas the accumulation of aromatic compounds was observed after straw degradation by P. chrysosporium.