Bacterial stem cells for enhancing biodiesel production from lignocellulosic feedstocks

该项目的目标是对细菌细胞进行基因编程，使其产生大量的三酰甘油（TAG），这是一种可以转化为生物柴油和工业溶剂的商品化学品。用于制造TAG的细菌种类被称为不透明红球菌（Rhodococuus opacus），它特别擅长将木质和纤维植物物质（即木质纤维素原料）中的能量转化为其他分子。然而，一个挑战是TAG合成的最佳条件不利于细胞生长，因此生产是自我限制的。该项目旨在通过将红球菌菌株转化为多细胞系统来解决这一问题，其中种群增长和TAG生产的任务分配给不同的细胞类型。如果这些菌株产生更多的TAG，它们可以通过将废弃的植物材料转化为有用的燃料来提高美国农业的效率。该项目还通过开发基于增强现实的课堂技术，为本科生物科学教育做出贡献。在这里，全息三维视频图像与传递可视化相结合，创造了一个充满活力和高度互动的社会学习环境。在共享的增强现实学习空间中，学生们以小团队的形式合作，通过酶途径和酶动力学的课程来加强学习。该技术方法的核心思想是通过插入一个基因工程系统来增强红球菌，该系统可以使两种独立的可编程细胞类型成为可能。在独立可控的细胞类型下，可以同时进行相互拮抗的任务。在这个项目中，两个相互拮抗的任务是高水平的三酰甘油（TAG）生产，这需要细胞进行氮剥夺并停止分裂，而人口增长则需要氮。为了最大限度地生产，一种被称为“工厂细胞”的细胞类型被编程停止吸收氮，并消耗所有可用的代谢资源来制造TAG。另一种被称为“干细胞”的细胞被设定为输入氮并进行不对称分裂。每次干细胞分裂后，一个子细胞保留干细胞命运，而另一个子细胞通过分化为工厂细胞进一步产生TAG。从分裂的干细胞群体中不断产生健康的新工厂细胞有望延长TAG合成时间并提高总体产量。该奖项反映了美国国家科学基金会的法定使命，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。

The goal of this project is to genetically program bacterial cells to make large quantities of triacylglycerol (TAG), a commodity chemical that can be converted to biodiesel and industrial solvents. The bacterial species that will be used to make TAG, called Rhodococuus opacus, is particularly good at converting the energy in woody and fibrous plant matter (i.e. lignocellulosic feedstocks) into other molecules. However, a challenge is that the optimal conditions for TAG synthesis are not conducive to cell growth, thus production is self-limiting. This project seeks to solve this problem by transforming Rhodococcus strains into multicellular systems, where the tasks of population growth and TAG production are assigned to different cell types. If the strains produce more TAG, they could be used to increase the efficiency of U.S. agriculture by transforming wasted plant material into useful fuel. This project also contributes to undergraduate biosciences education through the development of augmented reality-based classroom technology. Here, holographic three-dimensional video imagery is used in combination with pass- through visualization to create a vibrant and highly interactive social learning environment. Within shared, augmented reality learning spaces, students collaborate in small teams to enhance learning through lessons in enzyme pathways and enzyme kinetics.The technological approach centers on the idea of enhancing Rhodococcus by inserting a genetically engineered system that enables two independently programmable cell types. With independently controllable cell types, it is possible to carry out mutually antagonistic tasks simultaneously. In this project, the two mutually antagonistic tasks are high-level triacylglycerol (TAG) production, which requires that cells undergo nitrogen deprivation and stop dividing, and population growth, which requires nitrogen. For maximal production, one cell type, called a “factory cell”, is programmed to stop incorporating nitrogen and expend all available metabolic resources to make TAG. The other cell type, called a “stem cell”, is programmed to import nitrogen and divide asymmetrically. After each stem cell division, one daughter retains stem cell fate while the other furthers TAG production by differentiating into a factory cell. The continual generation of healthy new factory cells from the dividing stem cell population is expected to prolong TAG synthesis and lead to higher overall yield.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.