Fate of Labile Organic Carbon in Paddy Soil Is Regulated by Microbial Ferric Iron Reduction,Environmental Science & Technology

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Fate of Labile Organic Carbon in Paddy Soil Is Regulated by Microbial Ferric Iron Reduction
Environmental Science & Technology ( IF 10.8 ) Pub Date : 2019-07-17 , DOI: 10.1021/acs.est.9b01323
Jian-Xin Xu _{1,

2,

3,

4} , Xiao-Ming Li _{1,

5} , Guo-Xin Sun _{1,

5} , Li Cui ₆ , Long-Jun Ding ₁ , Chen He ₇ , Li-Guan Li ₂ , Quan Shi ₇ , Barth F. Smets ₂ , Yong-Guan Zhu _{1,

5,

6}

Affiliation

Global paddy soil is the primary source of methane, a potent greenhouse gas. It is therefore highly important to understand the carbon cycling in paddy soil. Microbial reduction of iron, which is widely found in paddy soil, is likely coupled with the oxidation of dissolved organic matter (DOM) and suppresses methanogenesis. However, little is known about the biotransformation of small molecular DOM accumulated under flooded conditions and the effect of iron reduction on the biotransformation pathway. Here, we carried out anaerobic incubation experiments using field-collected samples amended with ferrihydrite and different short-chain fatty acids. Our results showed that less than 20% of short-chain fatty acids were mineralized and released to the atmosphere. Using Fourier transform ion cyclotron resonance mass spectrometry, we further found that a large number of recalcitrant molecules were produced during microbial consumption of these short-chain fatty acids. Moreover, the biotransformation efficiency of short-chain fatty acids decreased with the increasing length of carbon chains. Ferrihydrite addition promoted microbial assimilation of short-chain fatty acids as well as enhanced the activation and biotransformation of indigenous stable carbon in the soil replenished with formate. This study demonstrates the significance of ferrihydrite in the biotransformation of labile DOM and promotes a more comprehensive understanding of the coupling of iron reduction and carbon cycling in paddy soils.

中文翻译：

微生物三价铁的还原调节水稻土中不稳定有机碳的命运

全球稻田土壤是甲烷（一种有力的温室气体）的主要来源。因此，了解稻田土壤中的碳循环非常重要。在稻田土壤中广泛发现的铁的微生物还原可能与溶解有机物（DOM）的氧化结合并抑制甲烷生成。然而，关于在淹没条件下积累的小分子DOM的生物转化以及铁还原对生物转化途径的影响知之甚少。在这里，我们进行了厌氧培养实验，使用的是野外采集的样品，并用三水铁矿和不同的短链脂肪酸进行了修饰。我们的结果表明，不到20％的短链脂肪酸被矿化并释放到大气中。使用傅立叶变换离子回旋共振质谱，我们进一步发现，在微生物消耗这些短链脂肪酸的过程中产生了大量的顽强分子。而且，短链脂肪酸的生物转化效率随着碳链长度的增加而降低。水铁矿的添加促进了短链脂肪酸的微生物同化，并增强了补充有甲酸盐的土壤中本地稳定碳的活化和生物转化。这项研究证明了水铁矿在不稳定DOM的生物转化中的重要性，并促进了对水稻土中铁还原和碳循环耦合的更全面的了解。短链脂肪酸的生物转化效率随着碳链长度的增加而降低。水铁矿的添加促进了短链脂肪酸的微生物同化，并增强了补充有甲酸盐的土壤中本地稳定碳的活化和生物转化。这项研究证明了水铁矿在不稳定DOM的生物转化中的重要性，并促进了对水稻土中铁还原和碳循环耦合的更全面的了解。短链脂肪酸的生物转化效率随着碳链长度的增加而降低。水铁矿的添加促进了短链脂肪酸的微生物同化，并增强了补充有甲酸盐的土壤中本地稳定碳的活化和生物转化。这项研究证明了水铁矿在不稳定DOM的生物转化中的重要性，并促进了对水稻土中铁还原和碳循环耦合的更全面的了解。

更新日期：2019-07-18

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