The theme ‘Lignocellulose biochemistry’ studies the changes in carbohydrates and of lignin during plant biomass conversion processes. These processes are not only limited to the more well-known biorefinery’s existing to produce food, fuels, and value-added chemicals from biomass, but also relating projects e.g. biomass composting for mushroom growth, or feed digestibility (animal nutrition) are part of this theme. Understanding of enzymatic routes to degrade the plant carbohydrates and lignin is a major topic within this theme.
This theme is headed by associate prof Dr. ir. Mirjam A. Kabel
Description of theme
We study mainly conversion of grasses, of which the plant cell walls are majorly composed of cellulose, hemicellulosic arabino-glucurono-xylan and of lignin. These three polymers contribute to the plant cell wall architecture, which influences physical characteristics like toughness (and degradability), and water binding capacity. A better understanding of the chemical fine-structure of the cell wall architecture’s network will provide a better understanding of how to influence changes in biomass architecture and it’s enzymatic (biological) degradation.
The aim of this theme is to (i) set up analysis for quantification and characterization of lignin; (ii) monitor changes in lignin and plant carbohydrate levels and composition during pretreatment, fungal growth, enzymatic processes, and during animal digestion; (iii) understand mode-of-action of hydrolytic and oxidative carbohydrate and lignin degrading enzymes and their effect on the chemical fine structure of natural substrates.
For the lignin analysis, we have set-up a new method via pyrolysis-GC-MS, making use of a mildly extracted 13C-lignin isolate from wheat straw as internal standard. This method allows us to specifically quantify residual lignin content in situ, while simultaneously providing structural insights. Further lignin characterisation via NMR (HSQC) has been set up. Carbohydrate analysis is applied in situ or/and after extraction polysaccharides. Examples of analysis are carbohydrate content and composition, the sugar linkage composition, the type and amount of substituents on the carbohydrates present. Various chromatographic and mass spectrometric techniques are available.
In carbohydrate biorefinery, structural composition studies are often closely related with the study of commercial and single-activity (hemi-)cellulases or esterases (enzymes). Currently, oxidative enzymes, such as laccases and the new lytic polysaccharide monooxygenases, are studied.