Nitrogenase Project

This project came out of the Nitrogen: Improving on Nature Ideas Lab that Maren participated in just as she was starting the lab. It involves Imperial College, London collaborators: A. William Rutherford, Martin Buck, and James Murray.

NSF Abstract: Nitrogen is most often the limiting nutrient to plant growth. While multiple bacteria and archaea have evolved the ability to fix atmospheric dinitrogen gas into biologically available ammonia using the nitrogenase enzyme, biological nitrogen fixation lacks wide applicability in agriculture. First, the process is energetically expensive. Second, all well-studied nitrogenase enzymes are inhibited by oxygen and require special structures to function effectively. However, there is a singular report of an oxygen insensitive nitrogenase system, isolated from a Streptomyces thermoautotrophicus bacterium found above burning charcoal fires in Germany. This superoxide dependent nitrogenase was only partially characterized and the strain is no longer available. The present project seeks to culture the original strain, as well as search for additional strains from similarly harsh environments that may harbor related nitrogenase systems. In particular, the project will target coal-seam fires and active volcanoes that have elevated levels of carbon monoxide; following the original isolation methods, strains will be cultivated under high temperatures with a carbon monoxide and carbon dioxide enriched atmosphere. Once identified, these strains will have their genome sequences determined and genes annotated. The soils from which they are isolated will also be sequenced to determine the aggregate meta-genome of all culturable and non-culturable microbes present in these harsh environments. The project will then seek to determine the biochemical and physiological properties of the nitrogenase systems in these organisms and attempt to transfer the oxygen-tolerant nitrogenase into other microbes for future biotechnology applications. The project has the potential to dramatically alter biological nitrogen fixation research and could ultimately lead to the engineering of plants that fix their own nitrogen.

Note that we extensively characterized both new and recovered S. thermo strains and they do not fix nitrogen! Check out the whole report in our Scientific Reports paperĀ doi:10.1038/srep20086.