The Potential and Challenges of Control over Alginate Production in Pseudomonas fluorescens for Use in Agriculture

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dc.contributor.advisorTabor, Jeffreyen_US
dc.creatorRoleck, Caleighen_US
dc.date.accessioned2024-08-30T15:52:38Zen_US
dc.date.available2024-08-30T15:52:38Zen_US
dc.date.created2024-08en_US
dc.date.issued2024-06-06en_US
dc.date.submittedAugust 2024en_US
dc.date.updated2024-08-30T15:52:38Zen_US
dc.description.abstractClimate change is creating an urgent need for new technologies to allow agriculture to adapt to predicted increases in drought severity. Exopolysaccharides (EPS) and EPSproducing bacteria are one potential solution, as previous studies have found EPS-treated soil has higher water potential than soils without EPS at the same water content level, thus better facilitating movement of water into plant roots in drier soils. However, EPSproducing bacteria and other plant growth promoting bacteria suffer have inconsistent performance due to the complex regulation controlling these functions. Using synthetic biology to uncouple these functions from their native regulation and place them under synthetic, predictable regulation is one potential solution, though it is limited by the level of current knowledge of these complex traits and potential fitness burdens that would be detrimental to field colonization. I engineered the soil bacteria Pseudomonas fluorescens for control over transcription of algR, the transcription factor responsible for regulating transcription of the genes for biosynthesis of the EPS alginate. While the system is not well studied in P. fluorescens, the alginate biosynthetic and regulatory system is highly conserved with Pseudomonas aeruginosa, for which the current mechanism of alginate regulation relies heavily upon differential transcription of algR. However, differential expression of algR in P. fluorescens did not allow for alginate production. Transcriptomics reveals that, unlike in P. aeruginosa, only one of the alginate biosynthetic transcripts is upregulated with increased AlgR. However, the other transcript’s expression patterns at various concentrations of AlgR reveals potential transcription factor cross-talk, and several potential candidates were identified. Deciphering this complex regulatory landscape is key to controlling alginate production, as directly controlling expression of these two transcripts might not be a viable strategy. Alginate production is metabolically intensive and may result in a fitness burden, however, P. fluorescens differentially regulates several other metabolic genes, which could serve to alter overall cellular processes for sustainable alginate production. From this thesis, I establish that deciphering the unique regulation of P. fluorescens’ algD operon and the overall impact of AlgR on fitness are important next steps in developing soil Pseudomonas species to promote plant growth and resilience under drought.en_US
dc.format.mimetypeapplication/pdfen_US
dc.identifier.citationRoleck, Caleigh. The Potential and Challenges of Control over Alginate Production in Pseudomonas fluorescens for Use in Agriculture. (2024). PhD diss., Rice University. https://hdl.handle.net/1911/117764en_US
dc.identifier.urihttps://hdl.handle.net/1911/117764en_US
dc.language.isoengen_US
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.en_US
dc.subjectalginateen_US
dc.subjectplant growth promoting bacteriaen_US
dc.subjectPseudomonas fluorescensen_US
dc.subjectalgRen_US
dc.titleThe Potential and Challenges of Control over Alginate Production in Pseudomonas fluorescens for Use in Agricultureen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentSystems, Synthetic and Physical Biologyen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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