Electrode-assisted acetoin production in a metabolically engineered Escherichia coli strain.
Electrode-assisted acetoin production in a metabolically engineered Escherichia coli strain.
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DOI：
10.1186/s13068-017-0745-9
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发表时间：
2017
影响因子：
6.3
通讯作者：
Gescher J
中科院分区：
文献类型：
--
作者：
Förster AH;Beblawy S;Golitsch F;Gescher J
本文介绍了大肠杆菌厌氧发酵葡萄糖生产乙偶姻的代谢工程。乙偶姻在工业食品生产中有着广泛的应用，并被认为是生物经济的平台化学品。然而，生物技术的生产往往受到阻碍的同时形成的几个最终产品的电子受体的情况下。此外，典型的生产菌株通常具有潜在的致病性。本研究的目的是克服这些限制，通过建立一个电极辅助发酵过程中的E。杆菌在这里，在生产过程中释放的过剩电子被转移到作为缺氧和非消耗性电子受体的电极。在第一步中，通过缺失编码厌氧碳代谢的中心反应酶的基因（ΔfrdA-D ΔadhE ΔldhA Δpta-ack），将中心代谢转向从葡萄糖生产丙酮酸。此后，乙酰乳酸合酶（alsS）和乙酰乳酸脱羧酶（alsD）的基因在该菌株中从质粒表达。添加硝酸盐作为电子受体导致厌氧乙偶姻生产，每摩尔葡萄糖消耗的产率高达0.9摩尔乙偶姻（理论最大值的90%）。在第二步中，用碳电极代替电子受体硝酸盐。这种相互作用需要从希瓦氏菌oneidensis的C型细胞色素的进一步表达和添加可溶性氧化还原穿梭亚甲蓝。与非耗尽型电子受体的相互作用导致乙偶姻形成，产率为理论最大值的79%（每摩尔葡萄糖0.79摩尔乙偶姻）。电极辅助发酵是一种新的策略，以生产比底物更氧化的生物技术价值的物质。在这里，我们第一次展示了一个过程，在这个过程中，常用的底盘应变E。大肠杆菌被定制用于从中心代谢物丙酮酸分支的电极辅助发酵方法。在这个早期阶段，我们看到了关于碳和电子回收的有希望的结果，并将使用进一步的菌株开发来增加厌氧代谢周转率。本文的在线版本（doi：10.1186/s13068-017-0745-9）包含补充材料，可供授权用户使用。
This paper describes the metabolic engineering of Escherichia coli for the anaerobic fermentation of glucose to acetoin. Acetoin has well-established applications in industrial food production and was suggested to be a platform chemical for a bio-based economy. However, the biotechnological production is often hampered by the simultaneous formation of several end products in the absence of an electron acceptor. Moreover, typical production strains are often potentially pathogenic. The goal of this study was to overcome these limitations by establishing an electrode-assisted fermentation process in E. coli. Here, the surplus of electrons released in the production process is transferred to an electrode as anoxic and non-depletable electron acceptor. In a first step, the central metabolism was steered towards the production of pyruvate from glucose by deletion of genes encoding for enzymes of central reactions of the anaerobic carbon metabolism (ΔfrdA-D ΔadhE ΔldhA Δpta–ack). Thereafter, the genes for the acetolactate synthase (alsS) and the acetolactate decarboxylase (alsD) were expressed in this strain from a plasmid. Addition of nitrate as electron acceptor led to an anaerobic acetoin production with a yield of up to 0.9 mol acetoin per mol of glucose consumed (90% of the theoretical maximum). In a second step, the electron acceptor nitrate was replaced by a carbon electrode. This interaction necessitated the further expression of c-type cytochromes from Shewanella oneidensis and the addition of the soluble redox shuttle methylene blue. The interaction with the non-depletable electron acceptor led to an acetoin formation with a yield of 79% of the theoretical maximum (0.79 mol acetoin per mol glucose). Electrode-assisted fermentations are a new strategy to produce substances of biotechnological value that are more oxidized than the substrates. Here, we show for the first time a process in which the commonly used chassis strain E. coli was tailored for an electrode-assisted fermentation approach branching off from the central metabolite pyruvate. At this early stage, we see promising results regarding carbon and electron recovery and will use further strain development to increase the anaerobic metabolic turnover rate. The online version of this article (doi:10.1186/s13068-017-0745-9) contains supplementary material, which is available to authorized users.