Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, Tianjin University of Science and Technology, Tianjin 300457, China; College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China.
College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China.
Bioresour Technol. 2020 Dec;318:124064. doi: 10.1016/j.biortech.2020.124064. Epub 2020 Sep 2.
One challenge in metabolic engineering for industrial applications is the construction of highly efficient microbial cell factories. For this purpose, dynamic regulation of metabolic flux may be indispensable. In this study, an auto-regulated Corynebacterium glutamicum chassis for 5-aminolevulinic acid (5-ALA) biosynthesis was constructed. First, the expression of critical genes involved in 5-ALA synthesis and cofactor regeneration was precisely modulated. Furthermore, odhA expression was controlled using the strategies of static metabolic engineering (SME, with a weak promoter), dynamic metabolic engineering (DME, with a temperature-sensitive plasmid), and auto-inducible metabolic engineering (AME, with a growth-related promoter). The AME strategy showed the best effect and dynamically balanced the tradeoff between cell growth and 5-ALA synthesis. Additionally, the expression of exporter-encoding rhtA was regulated using AME strategy by the two-component system HrrSA in response to extracellular heme. The final strain A30 achieved the highest 5-ALA production (3.16 g/L) ever reported in C. glutamicum through C5 pathway.
在用于工业应用的代谢工程中，一个挑战是构建高效的微生物细胞工厂。为此，代谢通量的动态调节可能是必不可少的。在这项研究中，构建了一种用于 5-氨基乙酰丙酸（5-ALA）生物合成的自动调节谷氨酸棒杆菌底盘。首先，精确调节了参与 5-ALA 合成和辅因子再生的关键基因的表达。此外，使用静态代谢工程（SME，使用弱启动子）、动态代谢工程（DME，使用温度敏感质粒）和自动诱导代谢工程（AME，使用与生长相关的启动子）来控制 odhA 的表达。AME 策略效果最好，动态平衡了细胞生长和 5-ALA 合成之间的权衡。此外，通过双组分系统 HrrSA 响应细胞外血红素，使用 AME 策略调节了外排剂编码 rhtA 的表达。最终的菌株 A30 通过 C5 途径实现了谷氨酸棒杆菌中 5-ALA 生产的最高记录（3.16 g/L）。
