Targeted discovery and functional characterisation of complex-xylan degrading enzymes
This thesis describes the development of a screening method to discover efficient hemicellulase producers in a wide range of fungi. The method is based on the potential of soil fungi to degrade soluble and insoluble xylan-rich substrates, by assigning various individual enzyme activities. Released mono- and oligosaccharides were monitored by high performance anion exchange chromatography and matrix assisted laser desorption/ionisation time-of-flight mass spectrometry. In addition, the released amounts of acetic acid were measured. Fungal strains, grown on wheat straw, with an efficient production of hemicellulolytic enzymes were Aspergillus lentulus, Penicllium pinophilum, and Trichoderma harzianum. Next, two glycoside hydrolase (GH) family 10 endo-xylanases and two GH11 endo-xylanases of Myceliophthora thermophila C1 (C1) were subjected to a detailed characterisation. The degradation products from xylan-rich substrates, varying in type and degree of substituents, displayed that both intra- and interfamily differences occurred for these endo-xylanases. The different degradation profiles were correlated with a difference in the predicted secondary protein structure of the GH10 xylanases and with a minor difference in the primary protein structure of the GH11 xylanases. An additional cellulose binding domain attached to the endo-xylanases did not enhance the degradation of insoluble substrates. In addition, synergy studies were performed on acetyl (xylan) esterases with glucuronidases. A concerted action of acetyl (xylan) esterases from different carbohydrate esterase families as well as synergy with glucuronidases of different GH families was observed.
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| Format: | Doctoral thesis biblioteca |
| Language: | English |
| Subjects: | enzymes, myceliophthora thermophila, soil fungi, xylan, xylanolytic microorganisms, bodemschimmels, enzymen, xylaan, xylanolytische micro-organismen, |
| Online Access: | https://research.wur.nl/en/publications/targeted-discovery-and-functional-characterisation-of-complex-xyl |
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