堆肥过程中木质素的降解机理及影响因素研究进展

农作物秸秆中的木质素作为自然界中含量丰富的高分子芳香族化合物，结构复杂，微生物难以降解，因此农业废弃物堆肥技术中，木质素的降解利用备受关注。研究表明:木质素是由结构单元通过碳碳键和醚键联接聚合而成，结构稳定。已有堆肥实验证明，木质素的微生物降解过程中真菌占主导地位，其分泌的漆酶、锰过氧化物酶和木质素过氧化物酶等以H₂O₂或O₂作为电子受体，能够使联接键断裂，使芳香烃结构去甲基化。多酚或酚类衍生物产物与氨基酸聚合，并进一步缩聚为腐殖质，用作土壤改良质还田。在实验室及自然条件下，大多数真菌对木质素的降解周期较长为30~60 d，降解率为20%~50%，其降解过程依赖于培养条件，特别在中温35~45℃和偏酸性条件下更利于木质素的降解。微生物代谢过程中存在最佳碳氮补充量，并且可以利用微量Mn2+、Cu2+诱导剂等提高木质素降解酶活性，这为调控堆肥过程木质素的降解和人工腐质化提供了重要的研究方向。

RESEARCH PROGRESS ON LIGNIN DEGRADATION MECHANISM AND INFLUENCING FACTORS DURING COMPOSTING

Lignin in crop stalks is a high-molecular aromatic compound abundant in nature. It has a complex structure and is difficult to degrade by microorganisms. Therefore, the degradation and utilization of lignin in agricultural waste composting technology has attracted much attention. Studies showed that lignin was formed by the polymerization of structural units through C-C bonds and ether bonds, and the structure was stable. Composting experiments proved that fungi dominate the process of microbial degradation of lignin. The secreted laccase, manganese peroxidase and lignin peroxidase used H₂O₂ or O₂ as the electron acceptors, which could break the bond, demethylate the aromatic hydrocarbon structure. The polyphenols or phenol produced were polymerized with amino acids, and further polycondensed into humus, which was used as a soil improvement substance to return to the field. Under laboratory and natural conditions, most fungi could degrade lignin for a long period of 30~60 days, with a degradation rate of 20%~50%. The degradation process depended on the culture conditions, the medium temperature 35~45℃ and acidic conditions were more conducive to the degradation of lignin. There was an optimal amount of carbon and nitrogen supplementation in the process of microbial metabolism, and trace Mn2+, Cu2+ inducers could be used to increase the activity of lignin degrading enzymes, which provided an important research direction for regulating the degradation of lignin and artificial humification during composting.