Chapter 4 Thermodynamic Control on Terminal Electron Transfer and Methanogenesis
Chapter 4 Thermodynamic Control on Terminal Electron Transfer and Methanogenesis
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第4章末端电子转移和产甲烷的热力学控制
DOI：
10.1021/bk-2011-1071.ch004
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发表时间：
2011
影响因子：
4.2
通讯作者：
C. Blodau
中科院分区：
文献类型：
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作者：
C. Blodau
末端电子接受过程（TEAP）控制缺氧环境中元素的命运。本研究的重点是氢依赖的TEAP的热力学调节。依赖氢气的甲烷生成和硫酸盐还原作用在接近自由能阈值（ΔGc）的情况下进行，并可因热力学条件的变化而受到抑制，而更“有效”的技经评估组则在远离其能量阈值的情况下进行，并将氢气浓度降低到排除其他技经评估组的水平。代谢自由能阈值取决于微生物生理学，当ATP生成所保存的能量接近热力学驱动力时发生。泥炭砂混合物的模型分析表明，乙酸碎屑甲烷生成可以抑制CH 4和溶解无机碳（DIC）的积累，降低自由能（ΔGr）的能量阈值（ΔGc），这是确定的逆模拟接近25 kJ mol-1。抑制对ΔGc和乙酸浓度敏感，因此ΔGc ± 5 kJ mol-1和1至100 μmol L-1乙酸浓度范围导致模型结果中稳态CH 4浓度的显著差异。
Terminal electron accepting processes (TEAPs) control the fate of elements in anoxic environments. This study focuses on thermodynamic regulation of H2-dependent TEAPs. H2-dependent methanogenesis and sulfate reduction operate near free energy thresholds (ΔGc) and can be inhibited by changes in thermodynamic conditions, whereas more ‘potent’ TEAPs occur far from their energy thresholds and lower H2 concentrations to levels that exclude other TEAPs. Metabolic free energy thresholds depend on microbial physiology and occur when the energy conserved byATP generation approaches the thermodynamic driving force. A model analysis for peat-sand mixtures suggests that acetoclastic methanogenesis can be inhibited by CH4 and dissolved inorganic carbon (DIC) accumulation, lowering the free energy (ΔGr) toward an energy threshold (ΔGc), which was identified by inverse modeling near 25 kJ mol-1. Inhibition was sensitive to ΔGc and acetate concentrations, so that ΔGc ± 5 kJ mol-1 and a range of 1 to 100 μmol L-1 acetate lead to strongly differing steady state CH4 concentrations in the model results.