Systems Biology and Medicine Laboratory, Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea; Systems Metabolic Engineering and Systems Healthcare Cross-Generation Collaborative Laboratory, KAIST, Daejeon, 34141, Republic of Korea.
Systems Metabolic Engineering and Systems Healthcare Cross-Generation Collaborative Laboratory, KAIST, Daejeon, 34141, Republic of Korea; Metabolic and Biomolecular Engineering National Research Laboratory, Department of Chemical and Biomolecular Engineering, KAIST Institute for BioCentury, KAIST, Daejeon, 34141, Republic of Korea.
Metab Eng. 2022 Nov;74:121-129. doi: 10.1016/j.ymben.2022.10.009. Epub 2022 Oct 29.
β-Alanine is an important β-amino acid with a growing demand in a wide range of applications in chemical and food industries. However, current industrial production of β-alanine relies on chemical synthesis, which usually involves harmful raw materials and harsh production conditions. Thus, there has been increasing demand for more sustainable, yet efficient production process of β-alanine. In this study, we constructed Corynebacterium glutamicum strains for the highly efficient production of β-alanine through systems metabolic engineering. First, aspartate 1-decarboxylases (ADCs) from seven different bacteria were screened, and the Bacillus subtilis ADC showing the most efficient β-alanine biosynthesis was used to construct a β-alanine-producing base strain. Next, genome-scale metabolic simulations were conducted to optimize multiple metabolic pathways in the base strain, including phosphotransferase system (PTS)-independent glucose uptake system and the biosynthesis of key precursors, including oxaloacetate and L-aspartate. TCA cycle was further engineered for the streamlined supply of key precursors. Finally, a putative β-alanine exporter was newly identified, and its overexpression further improved the β-alanine production. Fed-batch fermentation of the final engineered strain BAL10 (pBA2_tr18) produced 166.6 g/L of β-alanine with the yield and productivity of 0.28 g/g glucose and 1.74 g/L/h, respectively. To our knowledge, this production performance corresponds to the highest titer, yield and productivity reported to date for the microbial fermentation.
β-丙氨酸是一种重要的β-氨基酸,在化学和食品工业的广泛应用中需求不断增长。然而,目前β-丙氨酸的工业生产依赖于化学合成,这通常涉及有害的原材料和苛刻的生产条件。因此,人们对更可持续但高效的β-丙氨酸生产工艺的需求日益增加。在这项研究中,我们通过系统代谢工程构建了谷氨酸棒杆菌菌株,以高效生产β-丙氨酸。首先,筛选了来自七种不同细菌的天冬氨酸 1-脱羧酶(ADCs),并使用枯草芽孢杆菌 ADC 构建了β-丙氨酸生产的基础菌株,该酶显示出最有效的β-丙氨酸生物合成能力。接下来,进行了基因组规模的代谢模拟,以优化基础菌株中的多个代谢途径,包括磷酸转移酶系统(PTS)独立的葡萄糖摄取系统和关键前体的生物合成,包括草酰乙酸和 L-天冬氨酸。进一步对 TCA 循环进行了工程改造,以实现关键前体的简化供应。最后,新鉴定出一种推定的β-丙氨酸外排泵,并过表达该外排泵进一步提高了β-丙氨酸的产量。最终工程菌株 BAL10(pBA2_tr18)的分批补料发酵生产了 166.6 g/L 的β-丙氨酸,得率和生产效率分别为 0.28 g/g 葡萄糖和 1.74 g/L/h。据我们所知,这一生产性能与迄今为止微生物发酵报道的最高浓度、得率和生产效率相当。