Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843;
Department of Physical Geography, Stockholm University, 106 91 Stockholm, Sweden.
Proc Natl Acad Sci U S A. 2021 Nov 23;118(47). doi: 10.1073/pnas.2107668118.
Microbial growth is a clear example of organization and structure arising in nonequilibrium conditions. Due to the complexity of the microbial metabolic network, elucidating the fundamental principles governing microbial growth remains a challenge. Here, we present a systematic analysis of microbial growth thermodynamics, leveraging an extensive dataset on energy-limited monoculture growth. A consistent thermodynamic framework based on reaction stoichiometry allows us to quantify how much of the available energy microbes can efficiently convert into new biomass while dissipating the remaining energy into the environment and producing entropy. We show that dissipation mechanisms can be linked to the electron donor uptake rate, a fact leading to the central result that the thermodynamic efficiency is related to the electron donor uptake rate by the scaling law [Formula: see text] and to the growth yield by [Formula: see text] These findings allow us to rederive the Pirt equation from a thermodynamic perspective, providing a means to compute its coefficients, as well as a deeper understanding of the relationship between growth rate and yield. Our results provide rather general insights into the relation between mass and energy conversion in microbial growth with potentially wide application, especially in ecology and biotechnology.
微生物生长是在非平衡条件下出现的组织和结构的一个明显例子。由于微生物代谢网络的复杂性，阐明控制微生物生长的基本原理仍然是一个挑战。在这里，我们利用关于能量限制的单细胞培养生长的大量数据集，对微生物生长热力学进行了系统分析。基于反应化学计量的一致热力学框架使我们能够量化微生物可以将多少可用能量有效地转化为新的生物质，同时将剩余的能量耗散到环境中并产生熵。我们表明，耗散机制可以与电子供体摄取率相关联，这一事实导致了一个中心结果，即热力学效率与电子供体摄取率的关系由标度律 [公式：见文本] 确定，与生长产率的关系由 [公式：见文本] 确定。这些发现使我们能够从热力学的角度重新推导出皮尔特方程，为计算其系数提供了一种方法，同时也加深了对生长速率和产率之间关系的理解。我们的结果为微生物生长中质量和能量转换之间的关系提供了相当普遍的见解，特别是在生态学和生物技术方面具有广泛的应用。
