Browsing by Subject "Nitrogen Fixation"

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    Investigating Nitrogen Fixation and Metabolic Pathways in the Plant Endophyte Gluconacetobacter diazotrophicus
    (2021-07) Schwister, Erin
    Reduction of the reliance upon synthetic fertilizers is critical for a more sustainable agricultural future. Plant endophytes, especially those that engage in biological nitrogen fixation, provide a potential route towards this end. In this work, a deeper understanding of the plant endophyte and nitrogen fixing bacterium Gluconacetobacter diazotrophicus is presented through the following four chapters. The first chapter provides contextual background on this important plant endophyte and its potential for use in agriculture. Following this introduction, a large-scale transposon library of G. diazotrophicus is explored in the second and third chapters through highthroughput sequencing in a transposon insertion sequencing (Tn-seq) study. This Tn-seq study explores gene essentiality relating to nitrogen fixation as well as nutrient metabolism in G. diazotrophicus through rapid characterization across the entire genome. Lastly, the fourth chapter describes genetic manipulations of several key genes in G. diazotrophicus, performed to improve extracellular ammonium production to construct a strain for potential use as a biofertilizer. This work provides a deeper understanding of the genetic mechanisms essential to nitrogen fixation in G. diazotrophicus as well as those essential for growth under varied environmental conditions. As a nitrogen-fixing plant endophyte, further exploration of G. diazotrophicus as a potential alternative to synthetic fertilization brings us closer to a more sustainable agricultural future.
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    SUSTAINABLE HYDROGEN, AMMONIUM, AND BIOFUELS PRODUCTION
    (2021-03) Knutson, Carolann
    Sustainable technologies are are often guided by our understanding of their natural equivalents. As such, our incomplete understanding of these natural processes limit our ability to design efficient and optimized synthetic schemes to address the challenges facing food and energy security. In particular, schemes using live organisms or purified proteins require that we either attempt to remove evolutionary features such as regulation or cope with unknown confounding factors resulting from the gaps in our knowledge. All three of the following chapters focus on furthering our understanding of the natural systems we wish to co-opt. The first chapter discusses producing biohydrogen via Azotobacter vinelandii, a soil bacterium that fixes nitrogen gas into ammonia aerobically using the enzyme, nitrogenase. Additionally, it shows how the produced biohydrogen can act as a proxy of nitrogenase activity such that we can quantify the in vivo inhibition that results from various nitrogenous compounds commonly found in the environment. The second chapter discusses growing green algae in turbidostat reactors as way to screen their compatibility with divergent growing technologies and commercial ventures. Lastly, the third chapter discusses how an oil-degrading marine bacterium, Marinobacter aquaeolei , produces wax esters via a partially defined wax ester biosynthesis pathway.