Managing the Nitrogen economy of bacteria

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We plan to address how the supply of one key nutrient for plant growth - nitrogen in a form that can be taken up by plants(i.e. ammonia) - can be supplied by soil dwelling bacteria. A lack of nitrogen supply to plants frequently limits their growth,and the use of chemically produced nitrogen fertilizers threatens the environment and is energetically expensive toproduce. Hence alternative methods to supply fixed nitrogen that are not dependent on fossil fuels or the application ofchemicals to the soil are desirable. We plan to investigate how the nitrogen economy of simple soil dwelling bacteria isestablished through the network of control systems operating to achieve optimal levels of ammonia within cells, and tomodify these control systems to then allow the export of ammonia or amino acids to the soil and hence to plants. Ammoniawill be produced by the action of the bacterial nitrogen fixing enzyme nitrogenase, and we will work out how the bacterialcell regulates this metabolic process in order to maximize its own resource use efficiency. This knowledge will allow us torewire the regulatory control for the purpose of enhancing agricultural productivity.To date some simple first pass attempts have been made to exploit bacterial ammonia export for plant growth, and somewhat surprisingly these one offs show promise in that plant growth is enhanced in a manner suggesting reduced nitrogen from the bacteria is becoming available to support plant growth.Hence successfully refining ammonia export by bacteria holds great promise.Our work requires that we accurately quantify various key small molecules and proteins used to determine the cellsnitrogen economy, and produce a scheme whereby we can intervene and create a situation where some of the nitrogenasederived ammonia is excreted from the bacterial cells to the outside without greatly sacrificing the growth and fitness of thenitrogen fixing bacteria. To do so we will use methodologies which capture the various players of the control systems inaction, allowing us to work out where the major points of regulation occur and how they might be modified to gain anammonia export function without losing the fitness of the organism. This approach requires that we combine experimentswith modelling of the nitrogen control schemes, and also deploy synthetic biology tools to produce new master generegulator proteins which will allow us to capture the control of the entire complex networks of genes needed for the cellsmanagement of its nitrogen economy. By combining these approaches with knowledge and parallel study of how soil dwelling bacteriaestablish close associations with plant roots and are competitive , and in particular how they gain carbon as an energy source from plants, weexpect to be able to in a sustainable way improve nitrogen supply to plants in order to improve crop yields. In addition, weplan to utilize the knowledge and understanding that is gained in this project to also develop renewable biotechnologicalprocesses for industrial production of nitrogen containing chemicals that is driven entirely by solar energy.