Biodegradation of Lignocellulose by White-Rot Fungi: Structural Characterization of Water-Soluble Hemicelluloses
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Biodegradation of Lignocellulose by White-Rot Fungi: Structural Characterization of Water-Soluble Hemicelluloses Ling-Ping Xiao & Zheng-Jun Shi & Yuan-Yuan Bai & Wei Wang & Xue-Ming Zhang & Run-Cang Sun
# Springer Science+Business Media New York 2013
Abstract In the biological pretreatment process, white-rot fungi are mostly used to degrade lignin and carbohydrates in lignocellulosic biomass. In this study, water-soluble hemicelluloses were recovered from birch wood (Betula alnoides) decayed by white-rot fungi (Ganoderma lucidum C7016) for different durations up to 16 weeks. Accordingly, the dimethyl sulfoxide (DMSO)-soluble hemicelluloses were isolated from the untreated birch wood as a comparison. Results showed that the fungal-degraded polysaccharides were acidic hemicelluloses having a high content of uronic acids ranging from 20.6 to 22.5 %. Gel permeation chromatography analysis demonstrated that the recovered water-soluble hemicelluloses had a lower average molecular weight (M w, 15,990–27,560 g mol −1 ) than that of the DMSO-soluble hemicelluloses (M w, 33,960 g mol −1 ). Fourier transform infrared spectroscopy, scanning electron microscopy, one- and two-dimensional nuclear magnetic resonance spectroscopy also revealed significantly changes between those of fungal degraded and DMSO-soluble hemicelluloses. It was proposed that the hemicelluloses with low molecular weights were easily removed from wood by fungal degradation. This research revealed the changes of hemicelluloses in fungal degradation in the natural environment, Electronic supplementary material The online version of this article (doi:10.1007/s12155-013-9302-y) contains supplementary material, which is available to authorized users. L.-P. Xiao : Z.-J. Shi : Y.-Y. Bai : X.-M. Zhang : R.-C. Sun (*) Beijng Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China e-mail: [email protected] W. Wang Institute of Microbiology, Beijing Forestry University, Beijing 10083, China R.-C. Sun State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China
which may enable the exploration of novel methods in bioconversion of lignocellulosic biomass for the production of biofuels and biopolymers, in addition to the development of new and better ways to protect wood from biodegradation by microorganisms. Keywords Betula alnoides . Hemicelluloses . White-rot fungi . Biodegradation . HSQC NMR . Birch wood
Introduction Wood and agricultural residues, as well as the dedicated energy crops, are the main feedstocks for renewable fuels, chemicals, and other value-added products from biomass. Lignocellulosic material (LCM), the most abundant renewable biomass on earth, is composed mainly of cellulose, hemicelluloses, and lignin. Both the cellulose and hemicellulose fractions are polymers of sugars and thereby a potential source of fermentable sugars, whereas lignin can be used for the production of chemicals, combined heat and power, and other purposes. Hemicelluloses consist of
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