Systematic metabolic engineering of Corynebacterium glutamicum for the industrial-level production of optically pure D-(−)-acetoin,Green Chemistry

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Systematic metabolic engineering of Corynebacterium glutamicum for the industrial-level production of optically pure D-(−)-acetoin
Green Chemistry ( IF 9.3 ) Pub Date : 2017-10-23 00:00:00 , DOI: 10.1039/c7gc02753b
Yufeng Mao _{1,

2,

3} , Jing Fu _{1,

2,

3} , Ran Tao _{1,

2,

3} , Can Huang _{1,

2,

3} , Zhiwen Wang _{1,

2,

3} , Ya-Jie Tang _{4,

5,

6,

7,

8} , Tao Chen _{1,

2,

3,

4,

5} , Xueming Zhao _{1,

2,

3}

Affiliation

Acetoin is a high-value-added industrial product and a promising bio-based platform chemical. The two chiral enantiomers of acetoin are important potential pharmaceutical intermediates. However, at present it is very expensive to produce optically pure acetoin using conventional chemical synthesis methods. While classical biocatalysis fulfils many key criteria of green chemistry, it also comes with many other disadvantages, e.g. complicated process engineering, the need for expensive substrates and/or inducers, problematic production strains, or unsatisfactory titers. By redirecting metabolic fluxes, fine-tuning the activities of key enzymes and improving the strains’ genetic stability, the systematically engineered strain CGR5 was constructed, which offered improved D-(−)-acetoin production with optical purity surpassing 99.9%. Furthermore, acetoin production was increased significantly by the optimization of dissolved oxygen levels and culture medium components. Under aerobic conditions, the best strain CGR7 produced 96.2 g L⁻¹ D-(−)-acetoin, with a productivity of 1.30 g (L h)⁻¹ in a 5 L batch fermenter. To the best of our knowledge, this is the first report on producing optically pure D-(−)-acetoin with the highest titer, without multi-stage fermentation, concentration of cells by centrifugation or other complicated process steps. The process therefore is efficient and environmentally friendly. These results furthermore demonstrate that the biosafety level 1 microorganism C. glutamicum is a competitive choice for industrial-level production of optically pure D-(−)-acetoin.

中文翻译：

谷氨酸棒杆菌的系统代谢工程，用于工业级生产光学纯的D -（-）-乙酰丙酮

乙缩醛是一种高附加值的工业产品，也是一种有前途的生物基平台化学品。丙酮的两种手性对映异构体是重要的潜在药物中间体。但是，目前使用常规化学合成方法生产光学纯的乙酰丁胺是非常昂贵的。尽管经典的生物催化方法满足了绿色化学的许多关键标准，但它还具有许多其他缺点，例如复杂的工艺工程，对昂贵的底物和/或诱导剂的需求，有问题的生产菌株或效价不令人满意。通过重定向代谢通量，微调关键酶的活性并改善菌株的遗传稳定性，构建了系统工程改造的菌株CGR5，该菌株提供了改良的D-（-）-乙醛的生产，光学纯度超过99.9％。此外，通过优化溶解氧水平和培养基成分，可显着提高乙酰丙酮的产量。在有氧条件下，最佳菌株CGR7在5 L分批发酵罐中产生了96.2 g L ^-1 D -（-）-乙酰丙酮，生产力为1.30 g（L h）^-1。据我们所知，这是关于生产具有最高滴度的光学纯D -（-）-乙醛酸的报道，未经多阶段发酵，通过离心或其他复杂的步骤浓缩细胞。因此，该过程是高效且环境友好的。这些结果进一步证明了生物安全等级为1的谷氨酸棒杆菌是工业上生产光学纯D -（-）-乙醛酸的竞争选择。

更新日期：2017-11-09

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