Engineering the bacterium Rhodopseudomonas palustris as a platform for electrosynthetic bioproduction

在全球气候变化和人口增长的背景下，需要用风能和太阳能等可再生能源取代化石燃料。然而，如果要更广泛地采用可再生能源，就需要新的存储技术来管理它们供应的电力与需求相比的波动。第二个全球性挑战是满足对可持续生产的化学品日益增长的需求，无论是用于燃料还是用于制造。该项目以基因工程细菌形成的电活性生物材料的形式，为能源储存和可持续化学品生产问题提供了一个全面的解决方案。电活性细菌可以与其环境中的金属相互作用，并与其内部代谢交换电子。被吸收的电子被用来提供能量和驱动化学反应。生物材料具有自我组装和自我修复的优势，并且它们在生长时捕获碳，从而减少其对环境的影响。该工程菌将在专门的电化学反应器中生长，从而实现安全的控制和有效的土地利用。该项目将使用细菌Rhodopterium palustris，它具有天然的电活性，也具有广泛的代谢能力。这包括能够利用光来产生能量，以及捕获二氧化碳（就像植物在光合作用时所做的那样）和氮气的能力。生物体还可以利用电流将简单分子转化为有用的化学物质，用于燃料或制造或细胞生长。我们的目标是设计Rh。palustris，使得其更有效地吸收电流，并有效地使用电输入来产生大量所需的分子。这将使电能能够转化为氢气等燃料并储存，或用于生产生物塑料等有用分子。细胞和电极之间的电流转移已经在Rh中得到证实。这表明了该项目的可行性。合成生物学是一种构建设计师生物体的方法，它使用标准化的遗传部分和模块化设计来更可预测地设计它们的行为。该项目需要为Rh开发新的遗传成分。沼泽我们将建立基因部分的文库，这将使我们能够控制某些基因表达的时间和强度。我们还将优化对Rh进行遗传改变的方法。palustris染色体和表达外源基因。这些工具也将对其他研究Rh的研究人员有用。我们还将对Rh如何在相关生物中传播进行基础研究。palustris在基因表达水平上吸收电子。这将告诉我们，我们可能需要如何改变基因表达，以引导生物体的能量和代谢途径进入有用的活动。同样，这将对其他希望设计Rh的研究人员有用。这些遗传工具和数据将使我们能够将基因引入Rh。这使它能够有效地输入电流，并产生有用的化学物质，它不能自然合成。我们还将添加遗传元件来控制这些不同活动之间的切换。最终，我们的目标是将所有这些新功能整合在一起，产生一种将电能转化为化学物质的原型生物。

In the context of global climate change and population growth, there is a need to replace fossil fuels with renewable sources of energy such as wind and solar power. However, if renewables are to be more widely taken up, new storage technologies are required to manage the fluctuations in the power they supply compared to demand. A second global challenge is meeting the growing demand for sustainably produced chemicals, both for fuels and for manufacturing.This project offers a comprehensive solution to the problems of energy storage and sustainable chemicals production, in the form of an electro-active biological material formed of genetically engineered bacteria. Electro-active bacteria can interact with metals in their environment and exchange electrons with their internal metabolism. Electrons that are taken up are used supply energy and to drive chemical reactions. Biological materials have the advantage of being self-assembling and self-repairing, and they capture carbon as they grow which decreases their environmental impact. The engineered bacteria would be grown in specialised electro-chemical reactors, allowing for secure containment and efficient use of land.This project will use the bacterium Rhodopseudomonas palustris, which is naturally electro-active and also has broad metabolic capabilities. This includes being able to harness light to produce energy, and the ability to capture both carbon dioxide (just as plants do when they photosynthesise) and nitrogen gases. The organism can also use electrical current to convert simple molecules into useful chemicals for fuels or manufacturing, or growth of the cell. We aim to engineer Rh. palustris so that it is more effective at taking up electrical current, and efficiently uses the electrical input to produce large amounts of desirable molecules. This would enable electrical energy to be converted into and stored as fuels such as hydrogen gas, or used for the production of useful molecules such as bio-plastics. Transfer of electrical current between cells and an electrode has already been demonstrated in Rh. palustris, showing the feasibility of this project. Synthetic biology is an approach to building designer organisms that uses standardised genetic parts and modular design to more predictably engineer their behaviour. This project requires the development of new genetic components for Rh. palustris. We will characterise libraries of genetic parts that will give us control over when and how strongly certain genes are expressed. We will also optimise methods for making genetic alterations to the Rh. palustris chromosome and expressing foreign genes. These tools will also be useful to other researchers who are working with Rh. palustris, and may be transferable to related organisms.We will also do fundamental research into how Rh. palustris takes up electrons, at the level of gene expression. This will inform us about how we might need to alter the gene expression to channel the organism's energy and metabolic pathways into useful activities. Again, this will be useful to other researchers looking to engineer Rh. palustris to produce desirable chemicals.Together, these genetic tools and data will enable us to introduce genes into Rh. palustris that give it the capability to effectively import electrical current, and to produce useful chemicals that it cannot naturally synthesise. We will also add genetic elements to control the switching between these different activities. Ultimately we aim to have integrated all these new functions together, producing a prototype organism for the conversion of electrical power to chemicals.