Rugbjerg Peter, Feist Adam M, Sommer Morten Otto Alexander
The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark.
Department of Bioengineering, University of California, San Diego, San Diego, CA, United States.
Front Bioeng Biotechnol. 2018 Nov 12;6:166. doi: 10.3389/fbioe.2018.00166. eCollection 2018.
High productivity of biotechnological strains is important to industrial fermentation processes and can be constrained by precursor availability and substrate uptake rate. Adaptive laboratory evolution (ALE) of MG1655 to glucose minimal M9 medium has been shown to increase strain fitness, mainly through a key mutation in the transcriptional regulator , which increases flux through central carbon metabolism and the glucose uptake rate. We wanted to test the hypothesis that a substrate uptake enhancing mutation can translate to increased productivity in a strain possessing a heterologous metabolite pathway. When engineered for heterologous mevalonate production, we found that E672K strains displayed 114-167% higher glucose uptake rates and 48-77% higher mevalonate productivities in glucose minimal M9 medium. This improvement in heterologous mevalonate productivity of the E672K strain is likely mediated by the elevated glucose uptake rate of such strains, which favors overflow metabolism toward acetate production and availability of acetyl-CoA as precursor. These results demonstrate the utility of adaptive laboratory evolution (ALE) to generate a platform strain for an increased production rate for a heterologous product.
生物技术菌株的高生产力对工业发酵过程很重要，并且可能受到前体可用性和底物摄取率的限制。已证明将MG1655适应性实验室进化（ALE）至葡萄糖基本M9培养基可提高菌株适应性，主要是通过转录调节因子中的一个关键突变，该突变增加了通过中心碳代谢的通量和葡萄糖摄取率。我们想测试这样一个假设，即底物摄取增强突变可以转化为具有异源代谢途径的菌株中生产力的提高。当对其进行工程改造以生产异源甲羟戊酸时，我们发现E672K菌株在葡萄糖基本M9培养基中显示出高114 - 167%的葡萄糖摄取率和高48 - 77%的甲羟戊酸生产力。E672K菌株异源甲羟戊酸生产力的这种提高可能是由这些菌株升高的葡萄糖摄取率介导的，这有利于向乙酸盐生产的溢流代谢以及乙酰辅酶A作为前体的可用性。这些结果证明了适应性实验室进化（ALE）用于生成一个提高异源产物生产率平台菌株的效用。
