|Title||Characterization of cell wall degrading enzymes from Chrysosporium lucknowense C1 and their use to degrade sugar beet pulp|
|Source||Wageningen University. Promotor(en): Harry Gruppen, co-promotor(en): Henk Schols. - [S.l.] : S.n. - ISBN 9789085859789 - 191|
|Publication type||Dissertation, internally prepared|
|Keyword(s)||celwandstoffen - microbiële afbraak - chrysosporium - enzymen - suikerbieten - bietenpulp - bioraffinage - cell wall components - microbial degradation - chrysosporium - enzymes - sugarbeet - beet pulp - biorefinery|
|Categories||Chemistry of Food Components|
Key words: Pectin, arabinan, biorefinery, mode of action, branched arabinose oligomers, ferulic acid esterase, arabinohydrolase, pretreatment
Sugar beet pulp is the cellulose and pectin-rich debris remaining after sugar extraction from sugar beets. In order to use sugar beet pulp for biorefinery purposes, these carbohydrates need to be degraded to fermentable monosaccharides.The influence of six mild sulfuric acid or water pretreatments at different temperatures on the enzymatic degradability of sugar beet pulp was examined. An optimal pretreatment of 15 min at 140 °C in water greatly facilitates the subsequent enzymatic cellulose degradation. Enzymatic degradation of pectin requires an array of different enzyme activities. To this end, cell wall degrading enzymes of the filamentous fungus Chrysosporium lucknowense C1 (C1) were purified and characterized. Four arabinohydrolases from C1 were characterized that released up to 80% of the arabinose present in sugar beet arabinan as monomers. A combination of three arabinohydrolases also released unknown branched arabinose oligomers, which were purified and identified using NMR analysis. With the help of these complex arabinose oligomers the mode of action of four C1 α-L-arabinohydrolases was determined to enable controlled and tailored degradation of arabinan. Complete degradation of sugar beet pulp also requires ferulic acid esterase activity. Three C1 ferulic acid esterases were purified and characterized, of which one could release up to 60% of ferulic acid from feruloylated sugar beet pectin oligomers, whereas the other two were more active toward feruloylated arabinoxylan.