Rao Leizhen, Gu Decheng, Xiang Xingjia, Zeng Jun, Wu Yucheng, Lin Xiangui, Christie Peter
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; University of the Chinese Academy of Sciences, Beijing, 100049, China.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; Anhui Province Key Laboratory of Wetland Ecological Protection and Restoration, School of Resources and Environmental Engineering, Anhui University, Hefei, 230031, China.
Environ Pollut. 2023 Sep 15;333:122105. doi: 10.1016/j.envpol.2023.122105. Epub 2023 Jun 23.
Lignin is a complex biopolymer comprising phenolic monomers with different degrees of methoxylation and may potentially enhance the degradation of soil pollutants such as polycyclic aromatic hydrocarbons (PAHs) through co-metabolism. However, the contribution of lignin constituents, including phenolic and methoxy subunits, to PAH biodegradation remains unclear. Here, p-hydroxybenzoate (pHBA), vanillate and methanol were selected to simulate phenolic units and methoxy groups of lignin. Soil microcosms receiving these compounds were established to evaluate their regulation on the bacterial community and PAH co-metabolism. There were different effects of different components on the biodegradation of a four-ring PAH, benzo(a)anthracene (BaA), as characterized using an isotopic tracer. Only vanillate significantly stimulated BaA mineralization to CO, with pHBA and methanol leading to no appreciable change in the allocation of BaA in soil compartments. The lignin constituents had differential impacts on the soil bacterial community, with substantial enrichment of methylotrophs occurring in methanol-supplemented microcosms. Both vanillate and pHBA selected several aromatic degraders. Vanillate caused additional enrichment of methylotrophs, suggesting structure-dependent stimulation of bacterial functional guilds by lignin monomers. Compared with its constituents, lignin produced more extensive responses in terms of bacterial diversity and composition and the fate of BaA. However, it was difficult to link BaA co-metabolism to any specific bacterial taxa in the presence of lignin or its subunits. The results indicate that the co-metabolism effects of lignin may not be directly associated with phenolic or methoxy metabolism but with its regulation of the soil microbiome.
木质素是一种复杂的生物聚合物，由具有不同甲氧基化程度的酚类单体组成，可能通过共代谢作用增强土壤污染物如多环芳烃（PAHs）的降解。然而，木质素成分（包括酚类和甲氧基亚基）对PAH生物降解的贡献仍不清楚。在此，选择对羟基苯甲酸（pHBA）、香草酸和甲醇来模拟木质素的酚类单元和甲氧基。建立了接受这些化合物的土壤微观生态系统，以评估它们对细菌群落和PAH共代谢的调控作用。使用同位素示踪剂表征发现，不同成分对四环PAH苯并（a）蒽（BaA）的生物降解有不同影响。只有香草酸显著刺激了BaA矿化生成CO，而pHBA和甲醇导致土壤各组分中BaA的分配没有明显变化。木质素成分对土壤细菌群落有不同影响，在添加甲醇的微观生态系统中出现了大量甲基营养菌的富集。香草酸和pHBA都选择了几种芳香降解菌。香草酸导致甲基营养菌进一步富集，表明木质素单体对细菌功能类群的刺激具有结构依赖性。与它的成分相比，木质素在细菌多样性和组成以及BaA的归宿方面产生了更广泛的反应。然而，在存在木质素或其亚基的情况下，很难将BaA共代谢与任何特定的细菌分类群联系起来。结果表明，木质素的共代谢作用可能不直接与酚类或甲氧基代谢相关，而是与其对土壤微生物群落的调控有关。
