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Lignin-hemicellulose complexes restrict enzymatic solubilization of mannan and xylan from dissolving pulp

Gubitz, G.M., Stebbing, D.W., Johansson, C.I., Saddler, J.N.
Applied microbiology and biotechnology 1998 v.50 no.3 pp. 390-395
Athelia rolfsii, Gloeophyllum, Thermomyces lanuginosus, beta-mannosidase, cellulose, chromatography, dissolving pulp, endo-1,4-beta-glucanase, enzymatic treatment, hemicellulose, polymerization, solubilization, spectroscopy, xylan, xylanases
Mannan and xylan present in bleached soft-wood dissolving pulp were found to be partially resistant to hemicellulases even after repeated enzyme treatment. Despite the additional effect of an endoglucanase from Gloeophyllum separium, which increased the accessibility of mannan and xylan to a mannanase from Sclerotium rolfsii and to a xylanase from Thermomyces lanuginosus, the enzyme mixture solubilized only half of the hemicellulose present in the pulp. Half of the remaining hemicellulose present in the pulp appeared to be entrapped within the cellulose matrix while the other half was associated with lignin-carbohydrate complexes. The latter hemicellulose portion was isolated and characterized. Chromatography and spectroscopic techniques revealed the presence of two types of lignin-carbohydrate complex, a galactoglucomannan-lignin complex (degree of polymerization DP 50-60) and a xylan-lignin complex (DP > 200).