Su Hsiang-Yen, Li Hua-Ying, Xie Cai-Yun, Fei Qiang, Cheng Ke-Ke
Engineering Research Center of Health Food Design & Nutrition Regulation, School of Chemical Engineering and Energy Technology, Dongguan University of Technology, Dongguan, 523808, China.
School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, 710049, China.
Biotechnol Biofuels. 2021 Jan 19;14(1):26. doi: 10.1186/s13068-021-01878-1.
Renewable chemicals have attracted attention due to increasing interest in environmental concerns and resource utilization. Biobased production of industrial compounds from nonfood biomass has become increasingly important as a sustainable replacement for traditional petroleum-based production processes depending on fossil resources. Therefore, we engineered an Enterobacter cloacae budC and ldhA double-deletion strain (namely, EC∆budC∆ldhA) to redirect carbon fluxes and optimized the culture conditions to co-produce succinic acid and acetoin.
In this work, E. cloacae was metabolically engineered to enhance its combined succinic acid and acetoin production during fermentation. Strain EC∆budC∆ldhA was constructed by deleting 2,3-butanediol dehydrogenase (budC), which is involved in 2,3-butanediol production, and lactate dehydrogenase (ldhA), which is involved in lactic acid production, from the E. cloacae genome. After redirecting and fine-tuning the E. cloacae metabolic flux, succinic acid and acetoin production was enhanced, and the combined production titers of acetoin and succinic acid from glucose were 17.75 and 2.75 g L, respectively. Moreover, to further improve acetoin and succinic acid production, glucose and NaHCO modes and times of feeding were optimized during fermentation of the EC∆budC∆ldhA strain. The maximum titers of acetoin and succinic acid were 39.5 and 20.3 g L at 72 h, respectively.
The engineered strain EC∆budC∆ldhA is useful for the co-production of acetoin and succinic acid and for reducing microbial fermentation costs by combining processes into a single step.
由于对环境问题和资源利用的关注度不断提高，可再生化学品已引起人们的关注。从非食用生物质中生物基生产工业化合物作为传统化石资源依赖型石油基生产工艺的可持续替代方案变得越来越重要。因此，我们构建了阴沟肠杆菌budC和ldhA双缺失菌株（即EC∆budC∆ldhA）以重新定向碳通量，并优化培养条件以共同生产琥珀酸和3-羟基丁酮。
在本研究中，对阴沟肠杆菌进行代谢工程改造以提高其在发酵过程中琥珀酸和3-羟基丁酮的联合产量。通过从阴沟肠杆菌基因组中删除参与2,3-丁二醇生产的2,3-丁二醇脱氢酶（budC）和参与乳酸生产的乳酸脱氢酶（ldhA）构建了菌株EC∆budC∆ldhA。在重新定向和微调阴沟肠杆菌代谢通量后，琥珀酸和3-羟基丁酮的产量得到提高，葡萄糖产生的3-羟基丁酮和琥珀酸的联合产量分别为17.75和2.75 g/L。此外，为了进一步提高3-羟基丁酮和琥珀酸的产量，在EC∆budC∆ldhA菌株发酵过程中优化了葡萄糖和NaHCO₃的补料方式和时间。在72 h时，3-羟基丁酮和琥珀酸的最大产量分别为39.5和20.3 g/L。
工程菌株EC∆budC∆ldhA可用于3-羟基丁酮和琥珀酸的联产，并通过将工艺合并为一步来降低微生物发酵成本。
