- Xylan is a major class of hemicellulosic polysaccharides found in the cell walls of plants, making it one of the most abundant biopolymers on Earth after cellulose. Structurally, xylan is composed of a backbone of β-(1→4)-linked xylose residues, often decorated with side chains such as arabinose, glucuronic acid, or acetyl groups, depending on the plant species and tissue type. This structural diversity contributes to the complexity and functionality of xylan within the plant cell wall, where it plays a critical role in providing strength, flexibility, and resilience to mechanical and environmental stresses.
- In plants, xylan functions as a structural polysaccharide that interacts with cellulose microfibrils and lignin, forming a tightly integrated matrix that contributes to the rigidity and integrity of secondary cell walls. This network is particularly important in woody tissues, grasses, and cereal crops, where xylan accounts for a significant fraction of the biomass. The variation in side-chain substitutions and branching patterns influences solubility and interactions, making xylan a highly adaptable component of plant architecture. Its role extends beyond physical support: xylan also affects water transport, pathogen defense, and growth regulation within the plant.
- From an industrial perspective, xylan is an important renewable resource with applications in bioenergy, food, and biotechnology. Hydrolysis of xylan produces xylo-oligosaccharides (XOS) and xylose, which can be further fermented into xylitol, bioethanol, or other value-added chemicals. XOS, in particular, are gaining attention as prebiotic compounds that promote the growth of beneficial gut bacteria, thereby contributing to digestive and metabolic health. Xylan and its derivatives are also employed as thickeners, stabilizers, and gelling agents in food processing, as well as in papermaking, where xylan improves pulp quality and paper strength.
- In biomedical research, xylan-derived oligosaccharides and xylitol have shown potential health benefits, including prebiotic activity, antioxidant properties, and roles in managing metabolic disorders such as diabetes. Moreover, advances in nanotechnology and biomaterials have opened avenues for using xylan in biodegradable films, hydrogels, and coatings, highlighting its potential as a sustainable alternative to petroleum-based polymers.
- A major scientific challenge lies in the enzymatic degradation of xylan, as its structural heterogeneity makes it resistant to complete hydrolysis. Specialized enzymes known as xylanases are required to break down the xylan backbone and its side chains, and these enzymes are of great interest in industries ranging from biofuel production to animal feed enhancement. The study of microbial xylanases has advanced significantly, contributing to more efficient biomass conversion technologies that aim to exploit xylan-rich agricultural residues.
