Metabolism of diazotrophic nitrogen fixing bacteria, insights from synthetic biology and metabolomics

氮是作物生长的主要限制性养分之一。为了解决这个问题，人们使用无机肥料来提高作物产量，但这需要付出高昂的环境代价。由专业细菌进行的生物固氮，将环境中的二氮转化为生物可利用的氨，并提出了一种替代的，更环保的方法。这个基于实验室的项目的重点是了解自由生活的植物联合细菌的代谢，特别是在固定过程中，通过采用一系列合成生物技术与代谢组学方法相结合。将从一系列细菌种属和突变体中采集样本，并使用靶向和非靶向代谢组学方法进行分析，包括超高效液相色谱（UPLC-MS）和核磁共振（NMR）光谱。这些互补的技术可以更好地了解自然固定，以及它对全球新陈代谢的影响。这些发现将为我们如何最大限度地提高氨和其他次生代谢产物的产量提供见解，以支持作物生长和减少对无机肥料的依赖。此外，我们的目标是利用我们对这一过程的更多了解，为未来的合成生物事业提供信息，例如产生新的突变体或嵌合细菌。还将开展工作，调查细菌和植物根部之间的营养/化学交换，以便我们开始了解这在真实的世界环境中如何发挥作用。初步工作发现，植物能够利用细菌固定的氮，在它们的组织中发现了同位素标记的氮。

One of the major limiting nutrients in crop growth is nitrogen. To tackle this, inorganic fertilisers are used to increase crop yield, however this comes at a high environmental cost. Biological nitrogen fixation, carried out by specialist bacteria, sees environmental dinitrogen converted into ammonia which is biologically available and presents an alternative, more environmentally friendly approach. This lab based project is focussed on understanding the metabolism of free living plant associative bacteria, particularly during the fixation process, by employing a range of synthetic biological techniques in conjunction with metabolomic approaches. Samples will be collected from a range of bacterial species and mutants and analysed using targeted and untargeted metabolomic methods, including Ultra High Performance Liquid Chromatography (UPLC-MS) and Nuclear Magnetic Resonance (NMR) spectroscopy. These complementary techniques allow for a better understanding of native fixation, and the effects it has on global metabolism. These findings will provide insights on how we might maximise the output of ammonia, and other secondary metabolites, to support increased crop growth and decrease inorganic fertiliser dependency. In addition, we aim to utilise our increased understanding of this process to inform future synthetic biological undertakings, for example generating new mutants or chimeric bacteria. Work will also be carried out investigating nutrient/chemical exchanges between bacteria and plant roots so that we can begin to see how this could work in real world contexts. Preliminary work has found that plants are able to utilise bacterially fixed nitrogen, with isotopically labelled nitrogen being found in their tissue.