Isolation and chemical structure characterization of enzymatic lignin from Populus deltoides wood

摘要

Cellulytic enzymes were used for the isolation and structural characterization of Populus deltoides wood lignin as a fast growing and important species in wood processing technology. The isolation was based on the hydrolysis and partial solubilization of wood xylan and cellulose using combination of Thricoderma lanuginosus xylanase, Aspergillus sp. plus, A. niger cellulase, and almond glycosidase, followed by lignin purification using Bacillus licheniformis alkaline protease (for hydrolysis of cellulase contamination). The structure of enzymatic lignin (EL) was elucidated using chemical analysis, Py-GC/MS, FTIR, and quantitative~(13)C-NMR techniques. Different lignin structures of acetylated and nonacetylated lignin preparation were calculated. P. deltoides EL has been determined to have an h: g: s ratio of 5:60: 35. Also, P. deltoides EL contained 0.59/Ar of β-O-4 moieties with small amounts of other structural units such as pino/syringyresinol (0.05/Ar), phenylcoumaran (0.05/Ar), and spirodienone (0.01/Ar). The degree of condensation was estimated at 20%.