Jiang Jiaping, Luo Yuanchan, Fei Peng, Zhu Zhengtong, Peng Jing, Lu Juefeng, Zhu Du, Wu Hui
State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, School of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China.
Key Lab of Bioprocess Engineering of Jiangxi Province, College of Life Sciences, Jiangxi Science and Technology Normal University, Nanchang, 330013, China.
Bioresour Bioprocess. 2024 Apr 5;11(1):34. doi: 10.1186/s40643-024-00749-5.
Escherichia coli MLB (MG1655 ΔpflB ΔldhA), which can hardly grow on glucose with little succinate accumulation under anaerobic conditions. Two-stage fermentation is a fermentation in which the first stage is used for cell growth and the second stage is used for product production. The ability of glucose consumption and succinate production of MLB under anaerobic conditions can be improved significantly by using acetate as the solo carbon source under aerobic condition during the two-stage fermentation. Then, the adaptive laboratory evolution (ALE) of growing on acetate was applied here. We assumed that the activities of succinate production related enzymes might be further improved in this study. E. coli MLB46-05 evolved from MLB and it had an improved growth phenotype on acetate. Interestingly, in MLB46-05, the yield and tolerance of succinic acid in the anaerobic condition of two-stage fermentation were improved significantly. According to transcriptome analysis, upregulation of the glyoxylate cycle and the activity of stress regulatory factors are the possible reasons for the elevated yield. And the increased tolerance to acetate made it more tolerant to high concentrations of glucose and succinate. Finally, strain MLB46-05 produced 111 g/L of succinic acid with a product yield of 0.74 g/g glucose. SYNOPSIS.
大肠杆菌MLB(MG1655 ΔpflB ΔldhA)在厌氧条件下几乎不能利用葡萄糖生长,琥珀酸积累量很少。两阶段发酵是指第一阶段用于细胞生长,第二阶段用于产物生产的发酵过程。在两阶段发酵过程中,通过在好氧条件下以乙酸盐作为唯一碳源,可以显著提高MLB在厌氧条件下消耗葡萄糖和生产琥珀酸的能力。然后,在此应用了在乙酸盐上生长的适应性实验室进化(ALE)。我们假设在本研究中琥珀酸生产相关酶的活性可能会进一步提高。大肠杆菌MLB46 - 05由MLB进化而来,它在乙酸盐上具有改善的生长表型。有趣的是,在MLB46 - 05中,两阶段发酵厌氧条件下琥珀酸的产量和耐受性显著提高。根据转录组分析,乙醛酸循环的上调和应激调节因子的活性是产量提高的可能原因。并且对乙酸盐耐受性的增加使其对高浓度葡萄糖和琥珀酸更具耐受性。最终,菌株MLB46 - 05生产了111 g/L的琥珀酸,产物得率为0.74 g/g葡萄糖。摘要。