Soil microbial enzymes may induce lignin decomposition, accompanied by generation of free radicals. The evolution of environmentally persistent free radicals (EPFRs) and reactive oxygen species (ROS) during laccase-catalyzed lignin decomposition remains unclear. Characterization by electron paramagnetic resonance spectroscopy revealed gradually increased concentration of EPFRs, with maximum levels within 6 h that remained constant, accompanied by the increase in g-factor from 2.0037 to 2.0041. The results suggested the generation of oxygen-centered radicals on lignin. The EPFRs produced on solid samples slowly decreased by 17.2% over 17 d. ROS were also detected to have a similar trend as that of the evolution of EPFRs. Scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, gel permeation chromatography and nuclear magnetic resonance analyses suggested the demethylation and oxidation of lignin. We clarify the biogeochemical transformation of lignin and potential contributions to the generation of EPFRs and ROS in soil.

中文翻译：

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漆酶分解木质素过程中环境持久性自由基的演变和稳定化。

土壤微生物酶可能诱导木质素分解，并伴随自由基的产生。漆酶催化的木质素分解过程中环境持久性自由基（EPFRs）和活性氧（ROS）的演变仍不清楚。通过电子顺磁共振波谱表征表明，EPFRs的浓度逐渐增加，在6小时内的最大水平保持恒定，同时g因子从2.0037增加到2.0041。结果表明在木质素上产生了以氧为中心的自由基。固体样品上产生的EPFR在17天内缓慢下降了17.2％。还检测到ROS具有与EPFR的进化相似的趋势。扫描电子显微镜，衰减全反射-傅立叶变换红外光谱，凝胶渗透色谱和核磁共振分析表明木质素的脱甲基和氧化。我们阐明了木质素的生物地球化学转化以及对土壤中EPFR和ROS生成的潜在贡献。