MCFADDEN B A, HOMANN H R
J Bacteriol. 1963 Nov;86(5):971-7. doi: 10.1128/jb.86.5.971-977.1963.
McFadden, Bruce A. (Washington State University, Pullman), and H. Robert Homann. Quantitative studies of the effect of organic substrates and 2,4-dinitrophenol on heterotrophic carbon dioxide fixation in Hydrogenomonas facilis. J. Bacteriol. 86:971-977. 1963.-Whole cells of Hydrogenomonas facilis under heterotrophic conditions fixed levels of C(14)O(2) which depended upon the nature of the carbon source being oxidized. It was established that oxidative rates varied as a function of p(CO2). Therefore, all studies were conducted in the presence of 1.5 mole% CO(2) in the gas phase. With glucose-grown cells supplied with glucose as substrate, the heterotrophic fixation was curtailed 98% by the addition of 8.3 x 10(-4)m 2,4-dinitrophenol (DNP). A coupling between reductive fixation of CO(2) and heterotrophic oxidation of substrate is consistent with the observed effect of DNP. The efficiency of coupling of fixation with oxidation was studied for acetate, d-glucose, l-glutamate, d,l-lactate, d-ribose, and succinate as substrates. Kinetic studies showed that the efficiency of coupling (expressed as disintegrations per minute of C(14) per microliter of O(2)) was initially time-variable for all substrates; however, it approached a constant value after 30 to 45 min for acetate, glutamate, lactate, and succinate. The initial variation of the ratio with time was due primarily to C(14)O(2) uptake, which was nonlinear with time. Control studies in the absence of exogenous substrate indicated that CO(2) fixation may also be linked to oxidation of endogenous stores accumulated during heterotrophic growth. d-Ribose appears to be the most promising substrate for short-term fixation studies owing to the rapid incorporation of C(14) and the unusually low endogenous fixation rate by cells grown on ribose. Calculations reveal that, after isotopic equilibrium has occurred, the amount of CO(2) utilized during glucose oxidation is almost 50% of O(2) uptake during the same interval. Even during succinate oxidation, which was shown to be coupled much less effectively with CO(2) fixation, the CO(2) utilized during the same interval is 8% of O(2) uptake.
麦克法登，布鲁斯·A.（华盛顿州立大学，普尔曼），以及H.罗伯特·霍曼。有机底物和2,4-二硝基苯酚对易变氢单胞菌中异养二氧化碳固定作用的定量研究。《细菌学杂志》86:971 - 977。1963年。——在异养条件下，易变氢单胞菌的全细胞固定的C¹⁴O₂水平取决于被氧化的碳源的性质。已确定氧化速率随p(CO₂)而变化。因此，所有研究均在气相中含有1.5摩尔% CO₂的条件下进行。对于以葡萄糖培养且以葡萄糖为底物的细胞，添加8.3×10⁻⁴m的2,4-二硝基苯酚（DNP）可使异养固定减少98%。CO₂的还原固定与底物异养氧化之间的偶联与观察到的DNP的作用一致。研究了以乙酸盐、d-葡萄糖、l-谷氨酸、d,l-乳酸、d-核糖和琥珀酸盐为底物时固定与氧化的偶联效率。动力学研究表明，偶联效率（以每微升O₂中C¹⁴的每分钟衰变数表示）对于所有底物最初都是随时间变化的；然而对于乙酸盐、谷氨酸、乳酸和琥珀酸盐，在30至45分钟后接近恒定值。该比率随时间的初始变化主要归因于C¹⁴O₂的摄取，其随时间呈非线性。在没有外源底物的对照研究表明，CO₂固定也可能与异养生长期间积累的内源性储存物的氧化有关。由于C¹⁴的快速掺入以及在核糖上生长的细胞异常低的内源性固定速率，d-核糖似乎是短期固定研究中最有前景的底物。计算表明，在同位素平衡发生后，葡萄糖氧化期间利用的CO₂量几乎是同一时间段内O₂摄取量的50%。即使在琥珀酸盐氧化期间（已表明其与CO₂固定的偶联效率低得多）同一时间段内利用的CO₂也是O₂摄取量的8%。
