Heijnen J J, Van Dijken J P
Department of Biochemical Engineering, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands.
Biotechnol Bioeng. 1992 Apr 5;39(8):833-58. doi: 10.1002/bit.260390806.
Correlations for the prediction of biomass yields are valuable, and many proposals based on a number of parameters (Y(ATP), Y(Ave), eta(o), Y(c), Gibbs energy efficiencies, and enthalpy efficiencies) have been published. This article critically examines the properties of the proposed parameters with respect to the general applicability to chemotrophic growth systems, a clear relation to the Second Law of Thermodynamics, the absence of intrinsic problems, and a requirement of only black box information. It appears that none of the proposed parameters satisfies all these requirements. Particularly, the various energetic efficiency parameters suffer from major intrinsic problems. However, this article will show that the Gibbs energy dissipation per amount of produced biomass (kJ/C-mod) is a parameter which satisfies the requirements without having intrinsic problems. A simple correlation is found which provides the Gibbs energy dissipation/C-mol biomass as a function of the nature of the C-source (expressed as the carbon chain length and the degree of reduction). This dissipation appears to be nearly independent of the nature of the electron acceptor (e.g., O(2), No(3) (-), fermentation). Hence, a single correlation can describe a very wide range of microbial growth systems. In this respect, Gibbs energy dissipation is much more useful than heat production/C-mol biomass, which is strongly dependent on the electron acceptor used. Evidence is presented that even a net heat-uptake can occur in certain growth systems.The correlation of Gibbs energy dissipation thus obtained shows that dissipation/C-mol biomass increases for C-sources with smaller chain length (C(6) --> C(1)), and increases for both higher and lower degrees of reduction than 4. It appears that the dissipation/C-mol biomass can be regarded as a simple thermodynamic measure of the amount of biochemical "work" required to convert the carbon source into biomass by the proper irreversible carbon-carbon coupling and oxidation/reduction reactions. This is supported by the good correlation between the theoretical ATP requirement for biomass formation on different C-sources and the dissipation values (kJ/C-mol biomass) found. The established correlation for the Gibbs energy dissipation allows the prediction of the chemotrophic biomass yield on substrate with an error of 13% in the yield range 0.01 to 0.80 C-mol biomass/(C)-mol substrate for aerobic/anaerobic/denitrifying growth systems.
用于预测生物质产量的相关性很有价值，基于多个参数（Y(ATP)、Y(Ave)、eta(o)、Y(c)、吉布斯能量效率和焓效率）的许多提议已经发表。本文批判性地研究了这些提议参数的性质，涉及它们对化能营养生长系统的普遍适用性、与热力学第二定律的明确关系、不存在内在问题以及仅需要黑箱信息的要求。结果表明，没有一个提议的参数能满足所有这些要求。特别是，各种能量效率参数存在重大的内在问题。然而，本文将表明，每产生单位生物质的吉布斯能量耗散（kJ/C-摩）是一个满足要求且不存在内在问题的参数。发现了一个简单的相关性，它将吉布斯能量耗散/C-摩生物质表示为碳源性质的函数（以碳链长度和还原度表示）。这种耗散似乎几乎与电子受体的性质无关（例如，O(2)、No(3)(-)、发酵）。因此，一个单一的相关性可以描述非常广泛的微生物生长系统。在这方面，吉布斯能量耗散比每C-摩生物质的产热更有用，产热强烈依赖于所使用的电子受体。有证据表明，在某些生长系统中甚至可能发生净吸热。由此获得的吉布斯能量耗散的相关性表明，对于链长较小的碳源（C(6)→C(1)），耗散/C-摩生物质增加，对于还原度高于或低于4的情况，耗散也增加。似乎耗散/C-摩生物质可以被视为通过适当的不可逆碳-碳偶联和氧化/还原反应将碳源转化为生物质所需生化“功”量的一种简单热力学度量。不同碳源上生物质形成的理论ATP需求与所发现的耗散值（kJ/C-摩生物质）之间的良好相关性支持了这一点。所建立的吉布斯能量耗散相关性允许预测需氧/厌氧/反硝化生长系统中底物上的化能营养生物质产量，在产量范围为0.01至0.80 C-摩生物质/(C)-摩底物时，产量误差为13%。
