Lignin
Lignin is a complex organic polymer deposited in the extracellular matrix of plant cell walls, where it fills spaces between cellulose, hemicellulose, and pectin. It confers rigidity and hydrophobicity and helps resist microbial attack.
It is the second most abundant natural polymer on Earth after cellulose. Lignin is highly heterogeneous and
In vascular plants, lignin biosynthesis occurs via the phenylpropanoid pathway in specialized cells such as xylem
Structure features include a range of ether and carbon–carbon linkages, with the β-O-4 linkage being most common.
Function: Lignin provides mechanical strength, reduces cell wall porosity, controls water transport, and acts as a
Industrial relevance: Lignin is a major byproduct of pulping, paper production, and many biorefinery processes. It
Degradation and processing: Lignin is resistant to degradation due to its heterogeneity. Some white-rot fungi and
Variants: Technical lignin refers to lignin isolated from industrial processes; native lignin remains in plant cell