木质素在漆酶作用下降解过程中环境持久性自由基的演变和稳定。
Evolution and stabilization of environmental persistent free radicals during the decomposition of lignin by laccase.
机构信息
College of Natural Resources and Environment, Northwest A & F University, Yangling, 712100, China.
College of Natural Resources and Environment, Northwest A & F University, Yangling, 712100, China; State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Institute of Soil and Water Conservation, Northwest A & F University, Yangling, 712100, China.
出版信息
Chemosphere. 2020 Jun;248:125931. doi: 10.1016/j.chemosphere.2020.125931. Epub 2020 Jan 21.
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.
土壤微生物酶可能会诱导木质素分解，并伴随着自由基的产生。漆酶催化木质素分解过程中环境持久性自由基（EPFRs）和活性氧物种（ROS）的演变仍不清楚。通过电子顺磁共振波谱法进行的表征揭示了 EPFRs 的浓度逐渐增加，在 6 小时内达到最大值并保持不变，同时 g 因子从 2.0037 增加到 2.0041。结果表明在木质素上生成了以氧为中心的自由基。在 17 天内，固体样品中产生的 EPFRs 缓慢减少了 17.2%。还检测到 ROS 也呈现出与 EPFRs 演变相似的趋势。扫描电子显微镜、衰减全反射傅里叶变换红外光谱、凝胶渗透色谱和核磁共振分析表明木质素发生了去甲基化和氧化。我们阐明了木质素的生物地球化学转化及其对土壤中 EPFRs 和 ROS 生成的潜在贡献。
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