高糖酵解通量通过代谢工程改造的大肠杆菌菌株提高丙酮酸产量。

High glycolytic flux improves pyruvate production by a metabolically engineered Escherichia coli strain.

作者信息

Zhu Yihui, Eiteman Mark A, Altman Ronni, Altman Elliot

机构信息

Center for Molecular BioEngineering, Department of Biological and Agricultural Engineering, University of Georgia, Athens, GA 30602, USA.

出版信息

Appl Environ Microbiol. 2008 Nov;74(21):6649-55. doi: 10.1128/AEM.01610-08. Epub 2008 Sep 19.

Abstract

We report pyruvate formation in Escherichia coli strain ALS929 containing mutations in the aceEF, pfl, poxB, pps, and ldhA genes which encode, respectively, the pyruvate dehydrogenase complex, pyruvate formate lyase, pyruvate oxidase, phosphoenolpyruvate synthase, and lactate dehydrogenase. The glycolytic rate and pyruvate productivity were compared using glucose-, acetate-, nitrogen-, or phosphorus-limited chemostats at a growth rate of 0.15 h(-1). Of these four nutrient limitation conditions, growth under acetate limitation resulted in the highest glycolytic flux (1.60 g/g . h), pyruvate formation rate (1.11 g/g h), and pyruvate yield (0.70 g/g). Additional mutations in atpFH and arcA (strain ALS1059) further elevated the steady-state glycolytic flux to 2.38 g/g h in an acetate-limited chemostat, with heterologous NADH oxidase expression causing only modest additional improvement. A fed-batch process with strain ALS1059 using defined medium with 5 mM betaine as osmoprotectant and an exponential feeding rate of 0.15 h(-1) achieved 90 g/liter pyruvate, with an overall productivity of 2.1 g/liter h and yield of 0.68 g/g.

摘要

我们报道了在大肠杆菌菌株ALS929中丙酮酸的形成,该菌株在aceEF、pfl、poxB、pps和ldhA基因中存在突变,这些基因分别编码丙酮酸脱氢酶复合体、丙酮酸甲酸裂解酶、丙酮酸氧化酶、磷酸烯醇丙酮酸合酶和乳酸脱氢酶。在生长速率为0.15 h⁻¹的条件下,使用葡萄糖、乙酸盐、氮或磷限制的恒化器比较了糖酵解速率和丙酮酸生产率。在这四种营养限制条件中,乙酸盐限制下的生长导致了最高的糖酵解通量(1.60 g/g·h)、丙酮酸形成速率(1.11 g/g h)和丙酮酸产量(0.70 g/g)。atpFH和arcA基因的额外突变(菌株ALS1059)在乙酸盐限制的恒化器中将稳态糖酵解通量进一步提高到2.38 g/g h,异源NADH氧化酶的表达仅带来适度的额外改善。使用含有5 mM甜菜碱作为渗透保护剂的限定培养基,以0.15 h⁻¹的指数补料速率对菌株ALS1059进行分批补料培养,获得了90 g/L丙酮酸,总生产率为2.1 g/L h,产量为0.68 g/g。

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