Microbe-iron interactions control lignin decomposition in soil
Microbe-iron interactions control lignin decomposition in soil
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DOI：
10.1016/j.soilbio.2022.108803
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发表时间：
2022-08
影响因子：
9.7
通讯作者：
Cuijuan Liao;Wenjuan Huang;Jon Wells;Ruiying Zhao;K. Allen;E. Hou;Xin Huang;Han Qiu;F. Ta
中科院分区：
文献类型：
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作者：
Cuijuan Liao;Wenjuan Huang;Jon Wells;Ruiying Zhao;K. Allen;E. Hou;Xin Huang;Han Qiu;F. Ta
木质素分解与陆地碳（C）循环密切相关，这是由于木质素的巨大C质量及其在控制凋落物分解总体速率方面的重要性。在实验研究中，木质素与铁（Fe）矿物之间的相互作用越来越被认为是木质素分解的关键介质。然而，我们仍然缺乏一个定量的了解铁矿物如何与微生物相互作用，以控制木质素的分解。在这里，我们利用富铁土壤培养的实验结果，其中在四种预处理的O2可用性水平后，在有氧条件下测量了木质素分解速率，以利用MiFe模型来研究木质素分解中微生物-Fe（MiFe）的相互作用。我们量化了铁氧化还原循环如何与微生物活性相互作用，以控制木质素分解，通过数据模型集成。结果表明，与一级动力学模型和Michaelis-Menten动力学模型相比，具有时间依赖性生长和死亡函数的MiFe模型更好地描述了木质素分解过程中CO2的释放（R2范围为0.96 ~ 0.97）.在较低的O2利用率的预处理后，Fe（III）还原为Fe（II），刺激了芬顿反应，将大分子木质素分解为可供微生物利用的小分子。木质素和坏死物质的小分子与氧化的铁结合，并被保护免于分解。经过1年的培养，该模型表明，大部分的铁矿物稳定的C是来自小分子木质素C。我们对微生物-铁相互作用的定量分析为木质素的分解和保存提供了新的思路，并有助于改善全球变化下土壤C持久性的模型预测。
Lignin decomposition is critically linked to terrestrial carbon (C) cycle due to the enormous C mass of lignin and its importance in controlling overall rates of litter decomposition. Interactions between lignin and iron (Fe) minerals have been increasingly recognized as key mediators of lignin decomposition in experimental studies. However, we still lack a quantitative understanding of how Fe minerals interact with microbes to control lignin decomposition. Here, we leveraged experimental results from an incubation of Fe-rich soil, in which lignin decomposition rates were measured at aerobic conditions after four levels of pre-treated O2availability, to examine microbe-Fe (MiFe) interactions in lignin decomposition with a MiFe model. We quantified how Fe redox cycling interacted with microbial activities to control lignin decomposition via data-model integration. Our results showed that the MiFe model with time-dependent growth and mortality functions better represented CO2release from lignin decomposition (R2ranging from 0.96 to 0.97) than models assuming either first-order or Michaelis-Menten kinetics. Reduction of Fe(III) to Fe(II) after pre-treatments with lower O2availability stimulated the Fenton reaction to break down macro-molecular lignin into small molecules available to microbes. The small molecules of lignin and necromass bounded with oxidized Fe and were protected from decomposition. After 1-year incubation, the model implied that most of C stabilized with Fe minerals was derived from small molecular lignin C. Our quantitative analysis of microbe-Fe interactions sheds new light on lignin decomposition and preservation and helps improve model prediction of soil C persistence under global change.