Wang Xin, Su Rui, Chen Kequan, Xu Sheng, Feng Jiao, Ouyang Pingkai
State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing, China.
Front Microbiol. 2019 Feb 26;10:341. doi: 10.3389/fmicb.2019.00341. eCollection 2019.
Glutarate is an important C5 platform chemical produced during the catabolism of L-lysine through 5-aminovalerate (5-AMV) pathway. Here, we first established a whole-cell biocatalysis system for the glutarate production from L-lysine with the engineered () that co-expressed and . However, the accumulation of intermediate 5-AMV was identified as one important factor limiting glutarate production. Meanwhile, the negative interaction of co-expressing and in a single cell was also confirmed. Here, we solved these problems through engineering a microbial consortium composed of two engineered strains, BL21-22AB and BL21-YDT, as the whole-cell biocatalysts, each of which contains a part of the glutarate pathway. After the optimization of bioconversion conditions, including temperature, metal ion additives, pH, and cell ratio, 17.2 g/L glutarate was obtained from 20 g/L L-lysine with a yield of 95.1%, which was improved by 19.2% compared with that in a single cell. Little accumulation of 5-AMV was detected. Even at the high substrate concentration, the reduced 5-AMV accumulation and increased glutarate production were achieved. This synthetic consortium produced 43.8 g/L glutarate via a fed-batch strategy, the highest titer reported to date.
戊二酸是L-赖氨酸通过5-氨基戊酸（5-AMV）途径分解代谢过程中产生的一种重要的C5平台化学品。在此，我们首先建立了一个全细胞生物催化系统，用于从L-赖氨酸生产戊二酸，该系统采用了共表达[具体基因1]和[具体基因2]的工程化[具体菌株名称]。然而，中间产物5-AMV的积累被确定为限制戊二酸生产的一个重要因素。同时，在单个细胞中共表达[具体基因1]和[具体基因2]的负相互作用也得到了证实。在此，我们通过构建一个由两种工程化[具体菌株名称]菌株BL2l-22AB和BL2l-YDT组成的微生物群落作为全细胞生物催化剂来解决这些问题，每种菌株都包含戊二酸途径的一部分。在优化了包括温度、金属离子添加剂、pH值和细胞比例在内的生物转化条件后，从20 g/L L-赖氨酸中获得了17.2 g/L戊二酸，产率为95.1%，与单个细胞相比提高了19.2%。检测到5-AMV的积累很少。即使在高底物浓度下，也实现了5-AMV积累的减少和戊二酸产量的增加。这个合成群落通过补料分批策略生产了43.8 g/L戊二酸，这是迄今为止报道的最高滴度。
