During anaerobic digestion of organic waste, such as in producing biogas, which one of the following is left undegraded?

Explanation

Lignin is a complex polymer of phenylpropane units, which are cross-linked to each other with a variety of different chemical bonds. This complexity has thus far proven as resistant to microbial degradation. Cellulose is a long chain of glucose molecules, linked to one another primarily with glycosidic bonds. The simplicity of the cellulosic structure, using repeated identical bonds, means that only a small number of enzymes are required to degrade this material. Hemicellulose are branched polymers of xylose, arabinose, galactose, mannose, and glucose. Hemicellulose binds bundles of cellulose fibrils to form microfibrils, which enhances the stability of the cell wall but these can be degraded by increasing the number of enzymes.