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Lignin is found to be degraded by enzyme lignin peroxidases produced by some fungi like Phanerochaete chrysosporium. The mechanism by which lignin peroxidase (LiP) interacts with the lignin polymer involves veratrole alcohol , which is a secondary metabolite of white rot fungi that acts as a cofactor for the enzyme.
Production of lignin-peroxidase and manganese-peroxidase is the hallmark of basidiomycetes and is often used to assess basidiomycete activity, especially in biotechnology applications. [38] Most white-rot species also produce laccase, a copper-containing enzyme that degrades polymeric lignin and humic substances. [39]
Lignin-modifying enzymes benefit industry as they can break down lignin; a common waste product of the paper and pulp industry. These enzymes have been used in the refinement of poplar as lignin inhibits the enzymatic hydrolysis of treated poplar and Lignin-modifying enzymes can efficiently degrade the lignin thus fixing this problem. [4]
For example, laccases play a role in the formation of lignin by promoting the oxidative coupling of monolignols, a family of naturally occurring phenols. [ 1 ] [ 2 ] Other laccases, such as those produced by the fungus Pleurotus ostreatus , play a role in the degradation of lignin, and can therefore be classed as lignin-modifying enzymes . [ 3 ]
As they are present in food consumed in human diets and in plants used in traditional medicine of several cultures, their role in human health and disease is a subject of research. [ 1 ] [ 5 ] [ 6 ] [ 7 ] : 104 Some phenols are germicidal and are used in formulating disinfectants.
The first way white-rot fungi can break down lignin involves a high-redox-potential catalyzed peroxidase attack on the heme pocket, thus reducing the stability of lignin. The process starts with creation of extracellular hydrogen peroxide (H 2 O 2 ), a process completed via glyoxal oxidase (GLX).
A solution of hydrochloric acid and phloroglucinol is used for the detection of lignin (Wiesner test). A brilliant red color develops, owing to the presence of coniferaldehyde groups in the lignin. [44] Thioglycolysis is an analytical technique for lignin quantitation. [45] Lignin structure can also be studied by computational simulation. [46]
Lignin is a complex polymeric chemical compound that is a major constituent of wood. Resistant to biological decomposition, its presence in paper makes it weaker and more liable to discolor when exposed to light. The species C. bulleri contains three lignin-degrading enzymes: lignin peroxidase, manganese peroxidase, and laccase. [58]