Function of the iron-binding chelator produced by Coriolus versicolor in lignin biodegradation

摘要

An ultrafiltered low-molecular-weight preparation of chelating compounds was isolated from a wood-containing culture of the white-rot basidiomycete Coriolus versicolor.This preparation could chelate Fe3+ and reduce Fe3+ to Fe2+,demonstrating that the substance may serve as a ferric chelator,oxygen-reducing agent,and redox-cycling molecule,which would include functioning as the electron transport carrier in Fenton reaction.Lignin was treated with the iron-binding chelator and the changes in structure were investigated by 1H-NMR,13C-NMR,difference spectrum caused by ionization under alkaline conditions and nitrobenzene oxidation.The results indicated that the iron-binding chelator could destroy the beta-O-4 bonds in etherified lignin units and insert phenolic hydroxyl groups.The low-molecular-weight chelator secreted by C.versicolor resulted in new phenolic substructures in the lignin polymer,making it susceptible to attack by laccase or manganese peroxidase.Thus,the synergic action of the iron-binding chelator and the lignocellulolytic enzymes made the substrate more accessible to degradation.