Biodegradation of lignin-carbohydrate complexes |
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Authors: | Thomas W Jeffries |
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Institution: | (1) Institute for Microbial and Biochemical Technology, USDA Forest Service, Forest Products Laboratory, One Gifford Pinchot Drive, 53705-2398 Madison, WI, U.S.A. |
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Abstract: | Covalent lignin-carbohydrate (LC) linkages exist in lignocellulose from wood and groups herbaceous plants. In wood, they consist of ester and ether linkages through sugar hydroxyl to the -carbanol of phenylpropane subunits in lignin. In grasses, ferulic and p-coumaric acids are esterified to hemicelluloses and lignin, respectively. Hemicelluloses also contain substitutents and side groups that restrict enzymatic attack. Watersoluble lignin-carbohydrate complexes (LCCs) often precipitate during digestion with polysaccharidases, and the residual sugars are more diverse than the bulk hemicellulose. A number of microbial esterases and hemicellulose polysaccharidases including acetyl xylan esterase, ferulic acid esterase, and p-coumaric esterase attack hemicellulose side chains. Accessory hemicellulases include -l-arabinofuranosidase and -methyl-glucuranosidase. Both of these side chains are involved in LC bonds. -Glucosidase will attach sugar residues to lignin degradation products and when carbohydrate is attached to lignin, lignin peroxidase will depolymerize the lignin more readily.Abbreviations APPL
acid precipitable polymeric lignin
- CBQase
cellobioquinone oxidoreductase
- LC
lignincarbohydrate
- LCC(s)
lignin-carbohydrate complex
- DHP
Dehydrogenative polymerisate
- DMSO
dimethylsulfoxide
- DP
degree of polymerisation
- MWEL
milled wood enzyme lignin
- MWL
milled wood lignin (not digested with carbohydrases) |
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Keywords: | bonds carbohydrate lignin enzymatic degradation |
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