Metabolic Flux Analysis Elucidates the Importance of the Acid-Formation Pathways in Regulating Solvent Production by Clostridium acetobutylicum
Metabolic Flux Analysis Elucidates the Importance of the Acid-Formation Pathways in Regulating Solvent Production by Clostridium acetobutylicum
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DOI：
10.1006/mben.1999.0118
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发表时间：
1999-07-01
影响因子：
8.4
通讯作者：
Papoutsakis, Eleftherios T.
中科院分区：
文献类型：
--
作者：
Desai, Ruchir P.;Harris, Latonia M.;Papoutsakis, Eleftherios T.
采用代谢流分析方法研究丙酮丁醇梭菌产酸途径的作用。酸形成途径被揭示为在野生型发酵中起到与先前预期不同的作用。具体地，发现已知催化丁酸盐形成的酶摄取丁酸盐而不伴随丙酮的产生。过表达丁酸形成酶的重组菌株的通量分析进一步证实了这一作用。野生型发酵数据的分析还揭示了乙酸形成酶的重要作用，即在稳定期期间乙酸和乙酰辅酶A之间的碳循环。其次，利用代谢流分析比较了两种丁酸激酶缺陷型梭菌菌株的活性模式。丙酮丁醇通过基因失活开发的菌株PJC 4BK表现出酸形成通量向乙酸的转变，而通过反义RNA策略开发的菌株824（pRD 4）没有表现出这种转变。然而，这两种菌株都表现出改变的溶剂形成模式。PJC 4BK表现出强烈的瞬态增强溶剂形成通量。相比之下，824（pRD4）表现出相对较低水平的溶剂形成通量，虽然通量持续了较长的时间。(C)1999学术出版社
Metabolic flux analysis was used to investigate the roles of the acid formation pathways in Clostridium acetobutylicum. The acid formation pathways were revealed to serve different roles in wildtype fermentations than previously expected. Specifically, enzymes known to catalyze butyrate formation were found to uptake butyrate without concomitant production of acetone. This role was further corroborated by flux analysis of a recombinant strain overexpressing the butyrate formation enzymes. Analysis of wildtype fermentation data also revealed an important role for the acetate formation enzymes, namely the cycling of carbon between acetate and acetylCoA during the stationary phase. Next, metabolic flux analysis was used to compare the patterns of activity in two butyrate kinase deficient strains of C. acetobutylicum. The strain developed by gene inactivation, PJC4BK, exhibited a shift in acid formation fluxes toward acetate while the strain developed by antisense RNA strategies, 824(pRD4), did not exhibit such a shift. However, both strains exhibited altered solvent formation patterns. PJC4BK exhibited a strong transient enhancement of solvent formation fluxes. In contrast, 824(pRD4) exhibited relatively lower levels of solvent formation fluxes, although fluxes were sustained over a longer period of time. (C) 1999 Academic Press