Lignin, the most abundant aromatic material on Earth, is biodegraded by a unique enzymatic "combustion" process. This process involves nonspecific enzyme-catalyzed breakdown, and is central to the Earth's carbon cycle due to lignin's abundance and protective role over cellulose and hemicellulose. Research on lignin biodegradation has increased significantly in the past decade, with applications in pulping, bleaching, and waste treatment. Lignin is degraded by a narrower range of microbes than other biopolymers, and its degradation is primarily carried out by white-rot fungi, which are highly efficient in aerobic conditions. Lignin is a complex polymer composed of three precursor alcohols, forming a cross-linked, polydisperse structure. It is found in higher plants but not in liverworts or mosses. Lignin is interspersed within cell walls, forming a matrix around cellulose microfibrils. Lignin degradation is challenging due to its complex structure, requiring extracellular, nonspecific, and nonhydrolytic enzymes. Research has shown that lignin is not easily degraded anaerobically, and bacterial degradation is limited. White-rot fungi, however, are highly effective in degrading lignin, with some species capable of rapid and extensive degradation. White-rot fungi, such as Phanerochaete chrysosporium, degrade lignin through a series of oxidative reactions, including aromatic ring cleavage and depolymerization, leading to the formation of various low-molecular weight fragments. These fungi produce enzymes like ligninases, Mn peroxidases, and laccases, which are crucial for lignin degradation. Ligninase, a key enzyme, requires hydrogen peroxide and manganese ions, and is responsible for one-electron oxidation of lignin model compounds. Other enzymes, such as laccases, also play a role in phenol oxidation and may contribute to hydrogen peroxide production. The degradation of lignin by white-rot fungi is influenced by various factors, including nutrient availability, oxygen levels, and the presence of specific substrates. Lignin degradation by these fungi is often associated with secondary metabolism, which involves the production of various metabolites, including veratryl alcohol. The study of lignin degradation by white-rot fungi has provided insights into the biochemical and molecular mechanisms underlying this process, highlighting the importance of these fungi in the biodegradation of lignin.Lignin, the most abundant aromatic material on Earth, is biodegraded by a unique enzymatic "combustion" process. This process involves nonspecific enzyme-catalyzed breakdown, and is central to the Earth's carbon cycle due to lignin's abundance and protective role over cellulose and hemicellulose. Research on lignin biodegradation has increased significantly in the past decade, with applications in pulping, bleaching, and waste treatment. Lignin is degraded by a narrower range of microbes than other biopolymers, and its degradation is primarily carried out by white-rot fungi, which are highly efficient in aerobic conditions. Lignin is a complex polymer composed of three precursor alcohols, forming a cross-linked, polydisperse structure. It is found in higher plants but not in liverworts or mosses. Lignin is interspersed within cell walls, forming a matrix around cellulose microfibrils. Lignin degradation is challenging due to its complex structure, requiring extracellular, nonspecific, and nonhydrolytic enzymes. Research has shown that lignin is not easily degraded anaerobically, and bacterial degradation is limited. White-rot fungi, however, are highly effective in degrading lignin, with some species capable of rapid and extensive degradation. White-rot fungi, such as Phanerochaete chrysosporium, degrade lignin through a series of oxidative reactions, including aromatic ring cleavage and depolymerization, leading to the formation of various low-molecular weight fragments. These fungi produce enzymes like ligninases, Mn peroxidases, and laccases, which are crucial for lignin degradation. Ligninase, a key enzyme, requires hydrogen peroxide and manganese ions, and is responsible for one-electron oxidation of lignin model compounds. Other enzymes, such as laccases, also play a role in phenol oxidation and may contribute to hydrogen peroxide production. The degradation of lignin by white-rot fungi is influenced by various factors, including nutrient availability, oxygen levels, and the presence of specific substrates. Lignin degradation by these fungi is often associated with secondary metabolism, which involves the production of various metabolites, including veratryl alcohol. The study of lignin degradation by white-rot fungi has provided insights into the biochemical and molecular mechanisms underlying this process, highlighting the importance of these fungi in the biodegradation of lignin.