Biodegradation of Lignin by White-Rot Fungi

摘要

Pre-extracted birch wood chips were decayed with the white-rot fungus, Phanerochaete chrysosporium, to a weight loss of about 10 percent. The decayed chips were ground and the decayed wood meal was extracted with petroleum ether, chloroform, and methanol. The three biodegraded lignins were characterized by gel permeation chromatography, element analysis, and spectroscopy. The analytical and spectroscopic data indicate that the birch lignin undergoes extensive demethylation, oxidative cleavage of both chains and aromatic moieties, and reductions of unknown nature by the action of the fungus at the macro-molecular stage. Three possible interpretations of the data are made: (1) the demethylation could be associated with the oxidative cleavage of aromatic moieties; (2) the oxidative cleavages of side chains and aromatic moieties could result in the formation of aliphatic and aromatic acid units in the lignin; or (3) the reductions could be associated with catabolism of the lignin, and/or secondary anabolism resulting in addition of aliphatic groups to the lignin.