Vallino Joseph J
Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA.
Biol Bull. 2003 Apr;204(2):174-9. doi: 10.2307/1543554.
Biogeochemistry is the study of how living systems in combination with abiotic reactions process and cycle mass and energy on local, regional, and global scales (Schlesinger, 1997). Understanding how these biogeochemical cycles function and respond to perturbations has become increasingly important, as anthropogenic impacts have significantly altered many of these cycles (Galloway and Cowling, 2002; Houghton et al., 2002). Biogeochemistry is strongly governed by microbial processes, and it appears to closely follow thermodynamic constraints in that electron acceptor (O(2), NO(3)(-), SO(4)(2-), etc.) utilization closely follows a priori expectations based on energetics (Vallino et al., 1996; Hoehler et al., 1998; Jakobsen and Postma, 1999; Amend and Shock, 2001). Consortiums of microorganisms seem to have evolved to exploit chemical potentials wherever they exist in the environment, as manifested by the recent discovery of anaerobic methane oxidation by sulfate (Boetius et al., 2000) or sulfide oxidation by nitrate (Schulz et al., 1999). Three and a half billion years of natural selection have produced living systems capable of degrading most chemical potentials. We may therefore ask: If all ecosystem niche space is filled, is the biogeochemistry we observe in the environment dependent on the organisms that occupy that environment, or is the biogeochemistry determined by fundamental forces, with the evolution of living systems being the implementation of those forces? Recent developments in nonequilibrium thermodynamics (NET) are beginning to support the latter alternative, and advances in genomics are allowing us to explore microbial consortiums in detail. Taking advantage of ideas being suggested by NET, we have developed a modeling framework that views microbial consortiums as an inter-species distributed metabolic network. When combined with experimental observations, the model should help us test hypotheses that govern how living systems function.
生物地球化学研究的是生命系统如何与非生物反应相结合，在局部、区域和全球尺度上处理和循环物质与能量（施莱辛格，1997年）。随着人为影响已显著改变了许多这些循环，了解这些生物地球化学循环如何运作以及对扰动做出反应变得越来越重要（加洛韦和考林，2002年；霍顿等人，2002年）。生物地球化学在很大程度上受微生物过程的支配，并且似乎严格遵循热力学约束，即电子受体（氧气、硝酸根离子、硫酸根离子等）的利用紧密遵循基于能量学的先验预期（瓦利诺等人，1996年；赫勒等人，1998年；雅各布森和波斯特马，1999年；阿门德和肖克利，2001年）。微生物群落似乎已经进化到能利用环境中任何存在的化学势，最近发现的硫酸盐厌氧氧化甲烷（博伊修斯等人，2000年）或硝酸盐氧化硫化物（舒尔茨等人，1999年）就体现了这一点。35亿年的自然选择产生了能够降解大多数化学势的生命系统。因此我们可能会问：如果所有生态系统的生态位空间都已被填满，那么我们在环境中观察到的生物地球化学是取决于占据该环境的生物，还是由基本力量决定生物地球化学，而生命系统的进化只是这些力量的体现？非平衡热力学（NET）的最新进展开始支持后一种观点，并且基因组学的进展使我们能够详细探索微生物群落。利用NET提出的观点，我们开发了一个建模框架，将微生物群落视为种间分布式代谢网络。当与实验观察结果相结合时，该模型应有助于我们检验关于生命系统如何运作的假设。
