Department of Molecular Biology and Biotechnology, University of Sheffield , Sheffield S10 2TN, U.K.
Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
J Phys Chem B. 2017 Apr 20;121(15):3787-3797. doi: 10.1021/acs.jpcb.6b12335. Epub 2017 Mar 16.
Cell doubling times of the purple bacterium Rhodobacter sphaeroides during photosynthetic growth are determined experimentally and computationally as a function of illumination. For this purpose, energy conversion processes in an intracytoplasmic membrane vesicle, the chromatophore, are described based on an atomic detail structural model. The cell doubling time and its illumination dependence are computed in terms of the return-on-investment (ROI) time of the chromatophore, determined computationally from the ATP production rate, and the mass ratio of chromatophores in the cell, determined experimentally from whole cell absorbance spectra. The ROI time is defined as the time it takes to produce enough ATP to pay for the construction of another chromatophore. The ROI time of the low light-growth chromatophore is 4.5-2.6 h for a typical illumination range of 10-100 μmol photons m s, respectively, with corresponding cell doubling times of 8.2-3.9 h. When energy expenditure is considered as a currency, the benefit-to-cost ratio computed for the chromatophore as an energy harvesting device is 2-8 times greater than for photovoltaic and fossil fuel-based energy solutions and the corresponding ROI times are approximately 3-4 orders of magnitude shorter for the chromatophore than for synthetic systems.
在光合作用生长过程中，紫色细菌球形红杆菌的细胞倍增时间是通过实验和计算确定的，其作为光照的函数。为此，基于原子细节结构模型描述了胞内膜囊泡（类囊体）中的能量转换过程。细胞倍增时间及其光照依赖性是根据类囊体的投资回报率 (ROI) 时间计算的，该时间是通过 ATP 产生率计算得出的，而类囊体在细胞中的质量比则是通过整个细胞吸收光谱实验确定的。ROI 时间定义为产生足够 ATP 以支付另一个类囊体构建所需的时间。在 10-100 μmol 光子 m s 的典型光照范围内，低光生长类囊体的 ROI 时间分别为 4.5-2.6 h，相应的细胞倍增时间分别为 8.2-3.9 h。当将能源支出视为一种货币时，作为能量收集装置的类囊体的收益成本比计算结果是光伏和基于化石燃料的能源解决方案的 2-8 倍，而对于合成系统，类囊体的 ROI 时间大约短 3-4 个数量级。
