Engineering ammonia production in free-living diazotrophs for plant fertilization
Abstract/Contents
- Abstract
- In this dissertation we engineer ammonia production in the plant-symbiotic associative diazotroph Azospirillum brasilense towards addressing the engineering grand challenge of nitrogen fixation. Our approach leverages synthetically controllable post-translational deactivation of glutamine synthetase by unidirectional adenylyltransferases (uATs) causing nitrogen over-fixation and release. We demonstrate that uAT strains can promote the growth of the model grass Setaria viridis in mono-association and prove using isotope labeling that 15N2 is transferred from the air into the plant specific chlorophyll derivative pheophytin. To improve our strains, we study the evolutionary pressure on ammonia production and show that multicopy genetic redundancy extends their ammonia production lifetime in culture. By finetuning multicopy uAT expression strength, we then demonstrate that an optimal expression strength maximizes ammonia production rate. These expression optimized multicopy strains further increase the growth promotion of Setaria viridis, as well as promote the growth of Zea mays in nitrogen-poor, non-sterile soil compared to wild-type and mock inoculation. Finally, we show throughout our work that uAT strains can be used as tools to probe questions in fundamental biology, such as what metabolism is regulated by ammonia versus glutamine.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2021; ©2021 |
| Publication date | 2021; 2021 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Schnabel, Tim |
|---|---|
| Degree supervisor | Sattely, Elizabeth |
| Thesis advisor | Sattely, Elizabeth |
| Thesis advisor | Endy, Andrew D |
| Thesis advisor | Huang, Kerwyn Casey, 1979- |
| Thesis advisor | Long, Sharon |
| Degree committee member | Endy, Andrew D |
| Degree committee member | Huang, Kerwyn Casey, 1979- |
| Degree committee member | Long, Sharon |
| Associated with | Stanford University, Department of Bioengineering |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Tim Schnabel. |
|---|---|
| Note | Submitted to the Department of Bioengineering. |
| Thesis | Thesis Ph.D. Stanford University 2021. |
| Location | https://purl.stanford.edu/ny103rx5921 |
Access conditions
- Copyright
- © 2021 by Tim Schnabel
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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