微生物代谢组学案例分析

领域：微生物,多组学/蛋白质组/代谢组/脂质组    资料类型：其他资料   

丁醇发酵限速步骤的发现和解决

研究对象：Escherichia coli

分析检测平台：LC/MS/MS（BIOTREE）

期刊：Metabolic Engineering


影响因子：8.201

发表时间：2017

摘要：

High titer 1-butanol production in Escherichia coli has previously been achieved by overexpression of a modified clostridial 1-butanol production pathway and subsequent deletion of native fermentation pathways. This strategy couples growth with production as 1-butanol pathway offers the only available terminal electron acceptors required for growth in anaerobic conditions. With further inclusion of other well-established metabolic engineering principles, a titer of 15 g/L has been obtained. In achieving this titer, many currently existing strategies have been exhausted, and 1-butanol toxicity level has been surpassed. Therefore, continued engineering of the host strain for increased production requires implementation of alternative strategies that seek to identify non-obvious targets for improvement. In this study, a metabolomics-driven approach was used to reveal a CoA imbalance resulting from a pta deletion that caused undesirable accumulation of pyruvate, butanoate, and other CoA-derived compounds. Using metabolomics, the reduction of butanoyl-CoA to butanol catalyzed by alcohol dehydrogenase AdhE2 was determined as a rate-limiting step. Fine-tuning of this activity and subsequent release of free CoA restored the CoA balance that resulted in a titer of 18.3 g/L upon improvement of total free CoA levels using cysteine supplementation. By enhancing AdhE2 activity, carbon flux was directed towards 1-butanol production and undesirable accumulation of pyruvate and butanoate was diminished. This study represents the initial report describing the improvement of 1-butanol production in E. coli by resolving CoA imbalance, which was based on metabolome analysis and rational metabolic engineering strategies.

研究背景：

丁醇是重要的化学品，在工业生产和燃料、能源方面都有广泛的利用。基于可再生原料的利用和环境友好型化工品生产的重要意义，近年来由微生物发酵进行丁醇生产成为研究热点。随着对工程菌的不断改造，发酵过程中代谢瓶颈也逐渐模糊，因此需通过使用代谢组学等更加强大的代谢途径研究工具进行可能靶点的发掘。