Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou, China.
FEMS Microbiol Ecol. 2014 Apr;88(1):107-20. doi: 10.1111/1574-6941.12274. Epub 2014 Jan 21.
Iron oxides and humic substances (humics) have substantial effects on biochemical processes, such as methanogenesis, due to their redox reactivity and ubiquitous presence. This study aimed to investigate how methanogenesis is affected by the common occurrence of these compounds, which has not been considered to date. The experiment was conducted with anoxic paddy soil microcosms receiving a humics surrogate compound (anthraquinone-2,6-disulfonate, AQDS) and three iron(III) oxides (ferrihydrite, hematite, and magnetite) differing in crystallinity and conductivity. Ferrihydrite suppressed methanogenesis, whereas AQDS, hematite, and magnetite facilitated methanogenesis. CH4 production in co-occurring ferrihydrite + AQDS, hematite + AQDS, and magnetite + AQDS cultures was 4.1, 1.3, and 0.9 times greater than the corresponding cultures without AQDS, respectively. Syntrophic cooperation between Geobacter and Methanosarcina occurred in the methanogenesis-facilitated cultures. Experimental results suggested that the conductive characteristics of iron(III) oxides was an important factor determining the methanogenic response to the co-occurrence of iron(III) oxides and humics in anaerobic paddy soil. This work indicated that the type of iron(III) oxides may significantly affect carbon cycling under anoxic conditions in natural wetlands.
铁氧化物和腐殖质（腐殖酸）由于其氧化还原反应性和普遍存在，对生化过程（如产甲烷作用）有重大影响。本研究旨在调查这些常见化合物的共同存在如何影响产甲烷作用，这一点迄今尚未得到考虑。该实验在缺氧稻田微宇宙中进行，接收腐殖质替代化合物（蒽醌-2,6-二磺酸盐，AQDS）和三种不同结晶度和电导率的铁（III）氧化物（水铁矿、赤铁矿和磁铁矿）。水铁矿抑制产甲烷作用，而 AQDS、赤铁矿和磁铁矿促进产甲烷作用。与不含 AQDS 的相应培养物相比，共存的水铁矿+AQDS、赤铁矿+AQDS 和磁铁矿+AQDS 培养物中的 CH4 产量分别增加了 4.1、1.3 和 0.9 倍。在促进产甲烷作用的培养物中发生了 Geobacter 和 Methanosarcina 之间的协同合作。实验结果表明，铁（III）氧化物的导电特性是决定铁（III）氧化物和腐殖质在厌氧稻田中共存时产甲烷作用响应的重要因素。这项工作表明，在自然湿地缺氧条件下，铁（III）氧化物的类型可能会显著影响碳循环。
