Institut für Bio- und Geowissenschaften, IBG-1: Biotechnologie, Forschungszentrum Jülich, D-52425 Jülich, Germany.
Microb Biotechnol. 2012 Jan;5(1):116-28. doi: 10.1111/j.1751-7915.2011.00310.x. Epub 2011 Oct 20.
Corynebacterium glutamicum, an established industrial amino acid producer, has been genetically modified for efficient succinate production from the renewable carbon source glucose under fully aerobic conditions in minimal medium. The initial deletion of the succinate dehydrogenase genes (sdhCAB) led to an accumulation of 4.7 g l(-1) (40 mM) succinate as well as high amounts of acetate (125 mM) as by-product. By deleting genes for all known acetate-producing pathways (pta-ackA, pqo and cat) acetate production could be strongly reduced by 83% and succinate production increased up to 7.8 g l(-1) (66 mM). Whereas overexpression of the glyoxylate shunt genes (aceA and aceB) or overproduction of the anaplerotic enzyme pyruvate carboxylase (PCx) had only minor effects on succinate production, simultaneous overproduction of pyruvate carboxylase and PEP carboxylase resulted in a strain that produced 9.7 g l(-1) (82 mM) succinate with a specific productivity of 1.60 mmol g (cdw)(-1) h(-1). This value represents the highest productivity among currently described aerobic bacterial succinate producers. Optimization of the production conditions by decoupling succinate production from cell growth using the most advanced producer strain (C. glutamicumΔpqoΔpta-ackAΔsdhCABΔcat/pAN6-pyc(P458S) ppc) led to an additional increase of the product yield to 0.45 mol succinate mol(-1) glucose and a titre of 10.6 g l(-1) (90 mM) succinate.
谷氨酸棒杆菌是一种已被广泛应用于工业生产氨基酸的模式菌株，其能够在有氧条件下，以可再生碳源葡萄糖为底物，在最小培养基中高效生产琥珀酸。最初敲除琥珀酸脱氢酶基因（sdhCAB）导致 4.7 g l(-1)（40 mM）琥珀酸的积累以及作为副产物的高浓度乙酸（125 mM）。通过敲除所有已知的产生乙酸途径的基因（pta-ackA、pqo 和 cat），乙酸的产量减少了 83%，而琥珀酸的产量增加到 7.8 g l(-1)（66 mM）。虽然过表达乙醛酸支路基因（aceA 和 aceB）或过量生产回补酶丙酮酸羧化酶（PCx）对琥珀酸的生产只有较小的影响，但同时过表达丙酮酸羧化酶和 PEP 羧化酶会导致产生 9.7 g l(-1)（82 mM）琥珀酸的菌株，其比生产速率为 1.60 mmol g (cdw)(-1) h(-1)。这一数值代表了目前描述的好氧细菌琥珀酸生产中最高的生产效率。通过使用最先进的生产菌株（C. glutamicumΔpqoΔpta-ackAΔsdhCABΔcat/pAN6-pyc(P458S) ppc）将琥珀酸的生产与细胞生长解耦，优化生产条件，使产物产率进一步提高到 0.45 mol 琥珀酸 mol(-1) 葡萄糖，浓度达到 10.6 g l(-1)（90 mM）。
