Extracellular enzymes catalyze plant litter decomposition, including enzymes that degrade holocellulose (E₂) and lignin (E₃). To estimate relative enzyme activities associated with observed patterns of hollocellulose (C₂) and lignin (C₃) decay, we set observed decay rates equal to reverse Michaelis-Menten equations. Results were consistent with empirical studies, showing a negative relationship of E₂/(E₂+E₃) to litter lignin content, C₃/(C₂+C₃), above a minimum threshold at which lignin begins to decay. This threshold was previously reported to be 40% lignin content, but our results demonstrated substantial variability with litter type and environment. To our knowledge, this is the first mechanistic explanation of microbial allocation of cellulolytic and ligninolytic enzymes as a function of the lignin concentration of the lignocellulose complex but raises further questions about factors controlling the threshold for lignin decay, such as nitrogen availability.

细胞外酶催化植物凋落物的分解，包括降解全纤维素（E ₂）和木质素（E ₃）的酶。为了估计与观察到的纤维素（C ₂）和木质素（C ₃）衰变模式相关的相对酶活性，我们将观察到的衰变速率设置为与反向Michaelis-Menten方程相等。结果与经验研究一致，表明E ₂ /（E ₂ + E ₃）与垫料木质素含量C ₃ /（C ₂ + C ₃）呈负相关。），高于木质素开始衰减的最低阈值。先前报道该阈值是木质素含量的40％，但我们的结果表明，随垫料类型和环境的不同而存在很大差异。据我们所知，这是纤维素分解酶和木质素分解酶微生物分配与木质纤维素复合物中木质素浓度的函数的第一个机理解释，但提出了有关控制木质素衰变阈值的因素（例如氮的利用率）的其他问题。