Kim Seung-Jin, Yoon Jihee, Im Dae-Kyun, Kim Yong Hwan, Oh Min-Kyu
1Department of Chemical and Biological Engineering, Korea University, Seongbuk-gu, Seoul, 02841 Republic of Korea.
2School of Energy and Chemical Engineering, UNIST, Ulju-gun, Ulsan, 44919 Republic of Korea.
Biotechnol Biofuels. 2019 Sep 3;12:207. doi: 10.1186/s13068-019-1547-z. eCollection 2019.
Formate converted from CO reduction has great potential as a sustainable feedstock for biological production of biofuels and biochemicals. Nevertheless, utilization of formate for growth and chemical production by microbial species is limited due to its toxicity or the lack of a metabolic pathway. Here, we constructed a formate assimilation pathway in and applied adaptive laboratory evolution to improve formate utilization as a carbon source in sugar-free conditions.
The genes related to the tetrahydrofolate and serine cycles from AM1 were overexpressed for formate assimilation, which was proved by the C-labeling experiments. The amino acids detected by GC/MS showed significant carbon labeling due to biomass production from formate. Then, 150 serial subcultures were performed to screen for evolved strains with improved ability to utilize formate. The genomes of evolved mutants were sequenced and the mutations were associated with formate dehydrogenation, folate metabolism, and biofilm formation. Last, 90 mg/L of ethanol production from formate was achieved using fed-batch cultivation without addition of sugars.
This work demonstrates the effectiveness of the introduction of a formate assimilation pathway, combined with adaptive laboratory evolution, to achieve the utilization of formate as a carbon source. This study suggests that the constructed could serve as a strain to exploit formate and captured CO.
由一氧化碳还原转化而来的甲酸盐作为生物燃料和生物化学品生物生产的可持续原料具有巨大潜力。然而，由于其毒性或缺乏代谢途径，微生物利用甲酸盐进行生长和化学品生产受到限制。在此，我们在[具体微生物名称未给出]中构建了一条甲酸盐同化途径，并应用适应性实验室进化来提高在无糖条件下作为碳源的甲酸盐利用率。
来自[具体微生物名称未给出]AM1的与四氢叶酸和丝氨酸循环相关的基因被过表达以进行甲酸盐同化，这通过碳标记实验得到证实。气相色谱/质谱检测到的氨基酸由于甲酸盐产生的生物量而显示出显著的碳标记。然后，进行了150次连续传代培养以筛选出利用甲酸盐能力提高的进化菌株。对进化突变体的基因组进行测序，发现突变与甲酸盐脱氢、叶酸代谢和生物膜形成有关。最后，在不添加糖的情况下使用补料分批培养从甲酸盐中实现了90 mg/L的乙醇产量。
这项工作证明了引入甲酸盐同化途径并结合适应性实验室进化以实现将甲酸盐作为碳源利用的有效性。这项研究表明构建的[具体微生物名称未给出]可作为利用甲酸盐和捕获的一氧化碳的菌株。
