Engineered solar-driven recycling systems for sustainable fertilisation
File(s)
Author(s)
Valton, Marine
Type
Thesis
Abstract
Harvesting food removes essential nutrients for plant growth, such as nitrogen and phosphorous, from the agricultural system. This is currently solved by applying chemical fertilisers, but their overuse contributes to environmental pollution with extensive societal costs. Despite attempts to replace them with nitrogen-fixing cyanobacteria, no global impact has been observed.
In this thesis, I have researched the use of the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 as a provider of biologically available nitrogen for both aqueous and terrestrial biomass production. Model co-culture systems were developed that enabled the transfer of nitrogen from Anabaena to a second engineered cyanobacterium, allowing its growth and metabolism. A new protocol for monitoring such co-cultures was developed and verified. Importantly, this protocol enables both singular and filamentous cyanobacteria to be quantified from the same sample. Contaminants were also isolated from an industrial algae pilot plant, with the intention to evaluate if the robustness of engineered biomanufacturing can be influenced by the implementation of co-cultures.
Finally, the same Anabaena strain was also tested as a fertiliser of wheat as a model crop plant. Importantly, it was demonstrated that the fertilisation capability of Anabaena is enhanced if it is applied alive, suggesting that continued nitrogen fixation may still take place even after application to soil. Comparisons with a chemical fertiliser indicated that Anabaena was similarly efficacious. However, the high cost of algae manufacturing hinders immediate commercial use, necessitating further research for higher cost efficiency.
Overall, this study demonstrates that N2-fixing cyanobacteria have the potential to make a difference to both terrestrial and liquid photosynthetic biomanufacturing. The work provides a foundation for continued research into an exciting field of research that has important potential implications for human livelihood and a more sustainable way of life.
In this thesis, I have researched the use of the nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120 as a provider of biologically available nitrogen for both aqueous and terrestrial biomass production. Model co-culture systems were developed that enabled the transfer of nitrogen from Anabaena to a second engineered cyanobacterium, allowing its growth and metabolism. A new protocol for monitoring such co-cultures was developed and verified. Importantly, this protocol enables both singular and filamentous cyanobacteria to be quantified from the same sample. Contaminants were also isolated from an industrial algae pilot plant, with the intention to evaluate if the robustness of engineered biomanufacturing can be influenced by the implementation of co-cultures.
Finally, the same Anabaena strain was also tested as a fertiliser of wheat as a model crop plant. Importantly, it was demonstrated that the fertilisation capability of Anabaena is enhanced if it is applied alive, suggesting that continued nitrogen fixation may still take place even after application to soil. Comparisons with a chemical fertiliser indicated that Anabaena was similarly efficacious. However, the high cost of algae manufacturing hinders immediate commercial use, necessitating further research for higher cost efficiency.
Overall, this study demonstrates that N2-fixing cyanobacteria have the potential to make a difference to both terrestrial and liquid photosynthetic biomanufacturing. The work provides a foundation for continued research into an exciting field of research that has important potential implications for human livelihood and a more sustainable way of life.
Version
Open Access
Date Issued
2023-11-16
Date Awarded
2024-03-01
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Jones, Prof. Patrik
Publisher Department
Life Sciences
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)