pH as a Primary Control in Environmental Microbiology: 1. Thermodynamic Perspective
pH as a Primary Control in Environmental Microbiology: 1. Thermodynamic Perspective
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DOI：
10.3389/fenvs.2018.00021
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发表时间：
2018-05-01
影响因子：
4.6
通讯作者：
Kirk, Matthew F.
中科院分区：
文献类型：
--
作者：
Jin, Qusheng;Kirk, Matthew F.
PH影响微生物的发生和分布。微生物通常生活在3-4个pH单位的范围内，根据生长的最佳pH，微生物被描述为嗜酸性、中性粒细胞和嗜碱性细胞。它们的生长速度随pH呈钟形或三角形曲线变化，反映了细胞结构完整性的pH限制以及pH对细胞新陈代谢的干扰。我们认为，pH也可以影响微生物呼吸的热力学和动力学，从而有助于塑造微生物群落的组成和功能。在这里，我们使用地球化学反应模型来研究环境pH如何控制缺氧环境中常见的氧化还原反应的能量产率，包括共养氧化、铁还原、硫酸盐还原和甲烷生成。结果表明，环境pH直接和间接地改变了能量产量。直接变化适用于消耗或产生质子的反应，而间接影响适用于所有氧化还原反应，来自于pH对化学形态的调节。结果还表明，能量产量对pH变化有强烈的响应，这可能调节微生物的相互作用，并有助于提高微生物代谢的pH限制。这些结果强调了pH作为微生物代谢控制的重要性，并提供了对pH变化对微生物群落组成和活动的潜在影响的洞察。在一篇配套论文中，我们继续探索微生物代谢动力学如何对pH变化做出反应，以及这些反应如何控制微生物相互作用的结果，包括微生物联盟的活动和成员。
pH influences the occurrence and distribution of microorganisms. Microbes typically live over a range of 3-4 pH units and are described as acidophiles, neutrophiles, and alkaliphiles, depending on the optimal pH for growth. Their growth rates vary with pH along bell- or triangle-shaped curves, which reflect pH limits of cell structural integrity and the interference of pH with cell metabolism. We propose that pH can also affect the thermodynamics and kinetics of microbial respiration, which then help shape the composition and function of microbial communities. Here we use geochemical reaction modeling to examine how environmental pH controls the energy yields of common redox reactions in anoxic environments, including syntrophic oxidation, iron reduction, sulfate reduction, and methanogenesis. The results reveal that environmental pH changes energy yields both directly and indirectly. The direct change applies to reactions that consume or produce protons whereas the indirect effect, which applies to all redox reactions, comes from the regulation of chemical speciation by pH. The results also show that energy yields respond strongly to pH variation, which may modulate microbial interactions and help give rise to the pH limits of microbial metabolisms. These results underscore the importance of pH as a control on microbial metabolisms and provide insight into potential impacts of pH variation on the composition and activity of microbial communities. In a companion paper, we continue to explore how the kinetics of microbial metabolisms responds to pH variations, and how these responses control the outcome of microbial interactions, including the activity and membership of microbial consortia.