Tiwari Rameshwar, Sathesh-Prabu Chandran, Lee Sung Kuk
School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea.
Front Bioeng Biotechnol. 2022 Aug 10;10:939248. doi: 10.3389/fbioe.2022.939248. eCollection 2022.
The present study elaborates on the propionic acid (PA) production by the well-known microbial cell factory EM42 and its capacity to utilize biomass-derived levulinic acid (LA). Primarily, the EM42 strain was engineered to produce PA by deleting the methylcitrate synthase (PrpC) and propionyl-CoA synthase (PrpE) genes. Subsequently, a LA-inducible expression system was employed to express (encoding thioesterase) from and (encoding propionyl-CoA: succinate CoA transferase) from to improve the PA production by up to 10-fold under flask scale cultivation. The engineered EM42:ΔCE: was used to optimize the bioprocess to further improve the PA production titer. Moreover, the fed-batch fermentation performed under optimized conditions in a 5 L bioreactor resulted in the titer, productivity, and molar yield for PA production of 26.8 g/L, 0.3 g/L/h, and 83%, respectively. This study, thus, successfully explored the LA catabolic pathway of as an alternative route for the sustainable and industrial production of PA from LA.
本研究阐述了著名的微生物细胞工厂EM42生产丙酸（PA）的情况及其利用生物质衍生的乙酰丙酸（LA）的能力。首先，通过删除甲基柠檬酸合酶（PrpC）和丙酰辅酶A合酶（PrpE）基因对EM42菌株进行工程改造以生产PA。随后，采用LA诱导表达系统来表达来自[具体来源1]的[具体基因1]（编码硫酯酶）和来自[具体来源2]的[具体基因2]（编码丙酰辅酶A：琥珀酸辅酶A转移酶），从而在摇瓶规模培养下将PA产量提高了10倍。经过工程改造的EM42:ΔCE:用于优化生物工艺以进一步提高PA生产滴度。此外，在5升生物反应器中于优化条件下进行的补料分批发酵，PA生产的滴度、生产率和摩尔产率分别达到26.8克/升、0.3克/升/小时和83%。因此，本研究成功探索了[具体微生物]的LA分解代谢途径，作为从LA可持续工业生产PA的替代途径。
