<br>通过大肠杆菌的多维工程从葡萄糖高效发酵生产 β-丙氨酸,Journal of Agricultural and Food Chemistry

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通过大肠杆菌的多维工程从葡萄糖高效发酵生产 β-丙氨酸
Journal of Agricultural and Food Chemistry ( IF 5.7 ) Pub Date : 2024-06-12 , DOI: 10.1021/acs.jafc.4c03492
Yufei Zhang _{1,

2} , Guoyan Zhang _{1,

2} , Huifang Zhang ₂ , Yuehui Tian ₁ , Jia Li ₁ , Junhua Yun ₁ , Hossain M Zabed ₁ , Xianghui Qi _{1,

2}

Affiliation

β-丙氨酸是一种有价值的 β 型氨基酸，由于其在食品调味品、营养补充剂、制药和化学工业中的多方面应用，其需求正在不断增加。然而，由于调节多个基因的复杂性和固有的生理限制，β-丙氨酸的可持续生物合成目前面临挑战，因为缺乏强大的菌株。在这里，在大肠杆菌中实施了系统代谢工程来克服这些限制。首先，招募高效的L-天冬氨酸-α-脱羧酶（ADC）用于β-丙氨酸生物合成。为了保存磷酸烯醇丙酮酸通量，我们随后通过灭活磷酸转移酶系统（PTS）并引入替代的非PTS系统来修改内源葡萄糖同化系统，这将β-丙氨酸产量增加至1.70 g/L。通过加强主通量、阻断旁路代谢等综合调控，协同改善关键前体草酰乙酸和L-天冬氨酸的供应，使β-丙氨酸滴度显着提高至3.43 g/L。接下来，通过启动子和非翻译区（UTR）工程优化 ADC 的表达。进一步的运输工程，包括破坏 β-丙氨酸输入蛋白 CycA 和异源表达 β-丙氨酸输出蛋白 NCgI0580，将 β-丙氨酸产量提高到 8.48 g/L。此外，玉米浆还被用来开发一种经济高效的培养基。最终菌株在补料分批发酵过程中产生了 74.03 g/L β-丙氨酸，葡萄糖产量为 0.57 mol/mol。

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Efficient Fermentative Production of β-Alanine from Glucose through Multidimensional Engineering of Escherichia coli

β-Alanine, a valuable β-type amino acid, is experiencing increased demand due to its multifaceted applications in food flavoring, nutritional supplements, pharmaceuticals, and the chemical industry. Nevertheless, the sustainable biosynthesis of β-alanine currently faces challenges due to the scarcity of robust strains, attributed to the complexities of modulating multiple genes and the inherent physiological constraints. Here, systems metabolic engineering was implemented in Escherichia coli to overcome these limitations. First, an efficient l-aspartate-α-decarboxylase (ADC) was recruited for β-alanine biosynthesis. To conserve phosphoenolpyruvate flux, we subsequently modified the endogenous glucose assimilation system by inactivating the phosphotransferase system (PTS) and introducing an alternative non-PTS system, which increased β-alanine production to 1.70 g/L. The supply of key precursors, oxaloacetate and l-aspartate, was synergistically improved through comprehensive modulation, including strengthening main flux and blocking bypass metabolism, which significantly increased the β-alanine titer to 3.43 g/L. Next, the expression of ADC was optimized by promoter and untranslated region (UTR) engineering. Further transport engineering, which involved disrupting β-alanine importer CycA and heterologously expressing β-alanine exporter NCgI0580, improved β-alanine production to 8.48 g/L. Additionally, corn steep liquor was used to develop a cost-effective medium. The final strain produced 74.03 g/L β-alanine with a yield of 0.57 mol/mol glucose during fed-batch fermentation.

更新日期：2024-06-12

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