Date of Award:
Master of Science (MS)
Chemistry and Biochemistry
Nitrogen is an important part of biological molecules like proteins and DNA and hence is essential for life as we know it. The most commonly found form of nitrogen is dinitrogen gas (N2) in the atmosphere, which is not accessible to most organisms. Conversion of N2 into a usable form (ammonia), occurs through an energy-demanding reaction called nitrogen fixation. As we think about sending humans to Mars, there is a need to develop technologies for nitrogen fixation to produce fertilizer and other valuable compounds to support life in those harsh conditions.
The Haber-Bosch process is used in industries on Earth to produce ammonia from N2 and H2 under 400-500◦C temperature and 150-250 atm pressure. While this has enabled low-cost fertilizer production on Earth, it is not sustainable and is impractical for manned missions to outer space. Some microorganisms can perform a similar reaction using an enzyme called nitrogenase. The biological process typically occurs under standard temperature and pressure and so is a more feasible and sustainable option. However, scalable biohybrid technologies are not well developed, especially for applications in outer space.
The overarching aim of this thesis is to lay the groundwork for biological technologies that can replace the industrial process and function in conditions where resources and nutrients are scarce. The work presented here will demonstrate a proof-of-concept system that can support bacterial growth by capturing both N2 and CO2 using low energy infra-red light, and H2 produced from water electrolysis. The bacterial culture generated can be utilized as a fertilizer for plant growth and food production, as well as support other microbes for production of bioplastics and pharmaceuticals.
Further, we developed a bacterial strain that can grow under low nitrogen concentrations (2% N2, compared to 78% in the Earth’s atmosphere). To our knowledge, this is this first time bacteria have been observed to grow with such low concentrations of N2. This strain will not only allow us to increase efficiencies of the hybrid system under conditions similar to Mars, but can also reveal genetic targets for further improvements. Taken together, these studies can help develop sustainable nitrogen fixation technologies for applications in outer space and may also provide a competitive alternative to the current industrial process on Earth.
Soundararajan, Mathangi, "Innovative Biological Solutions for Nitrogen Fixation" (2020). All Graduate Theses and Dissertations. 7761.