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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.
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]
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]
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).
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 ]
Wood is composed of primarily three types of tissue: lignin, cellulose, and hemicelluloses. White rot species of Polyporales are efficient degraders of the decay-resistant polymer lignin, leaving partially degraded cellulose as a residue. [13] Brown rot species break down the cellulose fibres, leaving a brittle, brown lignin residue.
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]
Guaiacol (/ ˈ ɡ w aɪ ə k ɒ l /) is an organic compound with the formula C 6 H 4 (OH)(OCH 3).It is a phenolic compound containing a methoxy functional group. Guaiacol appears as a viscous colorless oil, although aged or impure samples are often yellowish.