Exploiting dynamics and cell-to-cell variation in metabolic engineering

细胞可以被改造成从燃料到药品的各种产品。然而，产生这些产物的途径通常会降低细胞产量并增加成本。以某种方式打开和关闭这些途径可能会同时减轻负担并增加产量。 从概念上讲，这种方法类似于工作周和周末。它是基于这样一种想法，即工作和休息的结合可以导致比持续不断的努力更高的整体生产力。这项研究得到了高中生和大学生教育和培训机会的补充。这些学生将准备参加高科技劳动力。基因表达是嘈杂的，导致细胞之间的变异，在缺乏遗传多样性。细胞利用这种可变性来优化资源使用。这就提出了一个问题，即在基因表达中引入动力学和噪音是否有益。该项目的重点是外排泵输出的单萜蒎烯。泵输出有毒底物并提高生物合成产量，但过度表达它们会给细胞带来负担。泵水平多样化可能会让人们利用这些好处和成本。该项目围绕两个目标组织：（1）量化流出和变异持续时间的单细胞差异，以及（2）比较动态与静态泵表达菌株中的蒎烯生产。将使用延时显微镜结合微流体和定量图像处理来表征泵的可变性。还将测量具有不同泵表达方法的菌株之间的蒎烯产率。随机数学建模来预测泵表达动力学的影响将补充实验。总的来说，该项目将测试是否有可能利用代谢工程中的细胞间变异来提高产量。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Cells can be engineered to produce products ranging from fuels to pharmaceuticals. However, the pathways that produce these products often reduce cell yields and increase costs. Turning these pathways on and off in some pattern might simultaneously reduce the burden and increase production. Conceptually, this approach is similar to a work week and weekend. It is based on the idea that a combination of work and time off can result in higher overall productivity than sustained, constant effort. The research is complemented by educational and training opportunities for high school students and undergraduates. These students will be prepared to participate in a high-technology workforce.Gene expression is noisy, leading to variation between cells in the absence of genetic diversity. Cells exploit that variability to optimize resource use. This calls into question whether introducing dynamics and noise in expression of genes could be beneficial. This project focuses on efflux pumps that export the monoterpene pinene. Pumps export toxic substrates and improve biosynthetic yields, but overexpressing them burdens the cell. Diversifying pump levels may allow populations to exploit these benefits and costs. The project is organized around two objectives: (1) to quantify single-cell differences in efflux and the duration of variability, and (2) to compare pinene production in strains with dynamic versus static pump expression. Time lapse microscopy coupled with microfluidics and quantitative image processing will be used to characterize pump variability. Pinene yields between strains with different approaches to pump expression will also be measured. Stochastic mathematical modeling to predict the impact of pump expression dynamics will complement the experiments. Overall, this project will test whether it is possible to exploit cell-to-cell variation in metabolic engineering to enhance production.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.