The article by Kirk and Farrell provides an overview of the enzymatic degradation of lignin, a complex plant polymer, by microorganisms. Lignin is the most abundant renewable aromatic material on Earth and plays a crucial role in the carbon cycle by protecting cellulose and hemicelluloses from enzymatic hydrolysis. The biodegradation of lignin has gained significant attention due to its potential applications in pulping, bleaching, conversion to useful products, and waste treatment. The authors discuss the structural features of lignin, which include a heterogeneous, optically inactive, cross-linked, and highly polydisperse polymer. The degradation of lignin is characterized by extracellular, nonspecific, and nonhydrolytic processes, making it distinct from other biopolymer-degrading systems. The biodegradation of lignin is primarily driven by certain fungi, particularly white-rot fungi, which can rapidly and extensively degrade lignin under aerobic conditions. The article details the physiological, biochemical, and genetic aspects of lignin degradation by white-rot fungi, focusing on the enzyme ligninase, also known as lignin peroxidase. Ligninase is an extracellular enzyme that catalyzes the oxidation of lignin using hydrogen peroxide as an electron donor. The enzyme has been extensively characterized, and its mechanism of action involves one-electron oxidation and subsequent radical-mediated reactions. The authors also discuss other enzymes involved in lignin degradation, such as manganese peroxidases and laccase, which play roles in phenol oxidation and hydrogen peroxide production. The article highlights the importance of these enzymes in the overall degradation process and their potential for biotechnological applications. Overall, the review emphasizes the recent progress in understanding the mechanisms and applications of lignin biodegradation, particularly in the context of white-rot fungi and the enzymes involved in this process.The article by Kirk and Farrell provides an overview of the enzymatic degradation of lignin, a complex plant polymer, by microorganisms. Lignin is the most abundant renewable aromatic material on Earth and plays a crucial role in the carbon cycle by protecting cellulose and hemicelluloses from enzymatic hydrolysis. The biodegradation of lignin has gained significant attention due to its potential applications in pulping, bleaching, conversion to useful products, and waste treatment. The authors discuss the structural features of lignin, which include a heterogeneous, optically inactive, cross-linked, and highly polydisperse polymer. The degradation of lignin is characterized by extracellular, nonspecific, and nonhydrolytic processes, making it distinct from other biopolymer-degrading systems. The biodegradation of lignin is primarily driven by certain fungi, particularly white-rot fungi, which can rapidly and extensively degrade lignin under aerobic conditions. The article details the physiological, biochemical, and genetic aspects of lignin degradation by white-rot fungi, focusing on the enzyme ligninase, also known as lignin peroxidase. Ligninase is an extracellular enzyme that catalyzes the oxidation of lignin using hydrogen peroxide as an electron donor. The enzyme has been extensively characterized, and its mechanism of action involves one-electron oxidation and subsequent radical-mediated reactions. The authors also discuss other enzymes involved in lignin degradation, such as manganese peroxidases and laccase, which play roles in phenol oxidation and hydrogen peroxide production. The article highlights the importance of these enzymes in the overall degradation process and their potential for biotechnological applications. Overall, the review emphasizes the recent progress in understanding the mechanisms and applications of lignin biodegradation, particularly in the context of white-rot fungi and the enzymes involved in this process.