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

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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.