**1. Introduction**

Lignin is one of the most abundant aromatic heteropolymer on earth, it is a component of plant cell walls, along with cellulose and hemicelluloses [1, 2]. The structure of lignin varies depending on the type of plant, however, three main types are recognized: G-type lignin (guaiacil), found in hardwoods; GS type lignin (syringil) present in softwoods; and GSH lignins (p-hydroxyphenyl) in grasses [3, 4]. Lignin forms a non-reactive and insoluble material around the layer rich in cellulose, which stiffens the cell wall and protects it from microbial attack. The value of lignin in the industry becomes more promising, as it has great potential in the production of chemicals with higher value, requiring its depolymerization into oligo and monomeric aromatic compounds as well as uniform sets of desired aromatic products [4]. However, the natural degradation process is not completely clear. Some detailed molecular studies of lignin degradation are limited by the lack of methods to analyze the decomposition of it. C-labeled lignin has been used to identify several degraders [5]. Generally, tissues with a higher content of lignin, polyphenol, and wax, decompose more slowly [6]. The resistance of plant biomass biodegradation is directly

related to the presence of lignin. According to some authors, in nature, lignin mineralization is an enzyme-dependent process, which is catalyzed by complex ligninolytic enzyme systems composed of extracellular oxidoreductases, such as laccase (Lac) and peroxidases [7].
