GROWTH-INHIBITION AND PYRUVATE OVERFLOW DURING GLUCOSE-METABOLISM OF EUBACTERIUM-LIMOSUM ARE RELATED TO A LIMITED CAPACITY TO REASSIMILATE CO2 BY THE ACETYL-COA PATHWAY
GROWTH-INHIBITION AND PYRUVATE OVERFLOW DURING GLUCOSE-METABOLISM OF EUBACTERIUM-LIMOSUM ARE RELATED TO A LIMITED CAPACITY TO REASSIMILATE CO2 BY THE ACETYL-COA PATHWAY
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DOI：
10.1099/00221287-139-8-1861
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发表时间：
1993-08-01
期刊：
影响因子：
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通讯作者：
LINDLEY, ND
中科院分区：
文献类型：
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作者：
LEBLOAS, P;GUILBERT, N;LINDLEY, ND
对厌氧产乙酸菌Eubacterium limosum的生长特性进行了动力学研究。一个短暂的指数生长期与同型产乙酸发酵，其中所有分解代谢释放的CO2通过乙酰辅酶A途径被再同化。在此阶段，未观察到其他产物。导致混合酸发酵模式（乙酸盐和丁酸盐）的代谢的重大转变与线性生长期的开始一致。在这个减速生长期乙酸产量显着减少归因于有限的能力的酶负责还原生成的甲基供体内的乙酰辅酶A途径：CO2和H-2积累在气相中。还观察到丙酮酸溢出（以及较小程度的乳酸、甘油酸和一氧化碳积累），但丙酮酸-铁氧还蛋白氧化还原酶比活性保持恒定。在所有实验中，特定生物质形成速率与乙酰辅酶A形成速率直接相关。指数生长期延长和生产的所有化合物以外的乙酸减少时，培养基中补充钨，表明甲酸脱氢酶可能是限制乙酰辅酶A途径的正确功能的酶。
The growth characteristics of Eubacterium limosum, an anaerobic acetogen, have been described kinetically for fermentation of glucose. A short-lived exponential growth phase was associated with a homoacetogenic fermentation in which all catabolic CO2 liberated was reassimilated via the acetyl-CoA pathway. During this phase no additional products were observed. A major shift in the metabolism leading to a mixed-acid fermentation pattern (acetate and butyrate) occurred coincident with the onset of the linear growth phase. Significantly diminished yields of acetate in this decelerating growth period were attributed to the limited capacity of the enzymes responsible for reductive generation of methyl donor within the acetyl-CoA pathway: CO2 and H-2 accumulated in the gas phase. Pyruvate overflow (and to a lesser extent lactate, glycerate and carbon monoxide accumulation) were also observed, though pyruvate-ferredoxin oxidoreductase specific activity remained constant. In all experiments specific biomass formation rates were directly related to the rate of acetyl-CoA formation. The exponential growth phase was prolonged and the production of all compounds other than acetate was diminished when the medium was supplemented with tungsten, suggesting that formate dehydrogenase may be the enzyme limiting the correct functioning of the acetyl-CoA pathway.