Vasconcelos I, Girbal L, Soucaille P
Centre de Bioingénierie Gilbert Durand, UA-CNRS 544, Institut National des Sciences Appliquées, Toulouse, France.
J Bacteriol. 1994 Mar;176(5):1443-50. doi: 10.1128/jb.176.5.1443-1450.1994.
The metabolism of Clostridium acetobutylicum was manipulated, at neutral pH and in chemostat culture, by changing the overall degree of reduction of the substrate, using mixtures of glucose and glycerol. Cultures grown on glucose alone produced only acids, and the intracellular enzymatic pattern indicated the absence of butyraldehyde dehydrogenase activity and very low levels of coenzyme A-transferase, butanol, and ethanol dehydrogenase activities. In contrast, cultures grown on mixtures of glucose and glycerol produced mainly alcohols and low levels of hydrogen. The low production of hydrogen was not associated with a change in the hydrogenase level but was correlated with the induction of a ferredoxin-NAD reductase and a decreased level of NADH-ferredoxin reductase. The production of alcohols was related to the induction of a NAD-dependent butyraldehyde dehydrogenase and to higher expression of NAD-dependent ethanol and butanol dehydrogenases. The coenzyme A-transferase was poorly expressed, and thus no acetone was produced. These changes in the enzymatic pattern, obtained with cultures grown on a mixture of glucose and glycerol, were associated with a 7-fold increase of the intracellular level of NADH and a 2.5-fold increase of the level of ATP.
在中性pH值和恒化器培养条件下，通过使用葡萄糖和甘油的混合物改变底物的整体还原程度，对丙酮丁醇梭菌的代谢进行了调控。仅以葡萄糖为底物生长的培养物仅产生酸，细胞内酶谱显示不存在丁醛脱氢酶活性，辅酶A转移酶、丁醇和乙醇脱氢酶活性水平极低。相比之下，以葡萄糖和甘油混合物为底物生长的培养物主要产生醇类且氢气产量较低。氢气产量低与氢化酶水平的变化无关，但与铁氧化还原蛋白-NAD还原酶的诱导以及NADH-铁氧化还原蛋白还原酶水平的降低相关。醇类的产生与NAD依赖性丁醛脱氢酶的诱导以及NAD依赖性乙醇和丁醇脱氢酶的更高表达有关。辅酶A转移酶表达不佳，因此未产生丙酮。在以葡萄糖和甘油混合物生长的培养物中观察到的这些酶谱变化，伴随着细胞内NADH水平增加7倍和ATP水平增加2.5倍。
