Research Progress in the Biodegradation of Lignin (Review)

China is rich in lignocellulosic resources from agricultural waste. However, for a long time, the utilization rate of lignocellulosic resources has been relatively low, which has led to problems such as resource waste and environmental pollution. Lignocellulose is usually composed of cellulose, hemicellulose and lignin. Among them, some enzymatic hydrolysis products of lignin have an inhibitory effect on enzymes and microorganisms. In addition, its structure hinders the contact between cellulase or hemicellulase and their substrates, thus, affecting the degradation of cellulose and hemicellulose. Although the biodegradation of lignin has the advantages of environmental friendliness and low energy consumption, it still faces problems such as the lack of efficient degrading bacteria and degrading enzymes, and the poor stability of most natural degrading enzymes. This manuscript introduces the diverse structures of lignin and various methods for analyzing lignin structure, reviews the recent research progress and the advantages of biological methods for lignin degradation, enumerates the main microbial groups with lignin-degrading ability and the main characteristics of various lignin-degrading enzymes. Moreover, it summarizes the current challenges and future development prospects of lignin biodegradation, hoping to provide certain scientific references for in-depth research in this field.