Bioremediation of waste by the bacterium Rhodopseudomonas palustris

Rhodopseudomonas palustris is a photosynthetic bacterium capable of metabolising a broad range of substrates. It is a highly robust microorganism with a high tolerance for toxic conditions, making it an ideal candidate for the remediation of waste materials by metabolism. Our societies produce large amounts of waste materials, which require processing and safe disposal, but could instead be used as resources to produce fuel and energy or sustainably recycled into new materials. R. palustris can be used to process waste glycerol (a byproduct of biodiesel manufacture), and naturally produces hydrogen gas (a clean-burning fuel) as a byproduct of this process. R. palustris could potentially be used to bioremediate other waste materials and could be engineered to manufacture other useful products from this process. This thesis reports discoveries regarding the growth of R. palustris on previously untested substrates and the engineering of R. palustris to improve its utilisation of substrates and add additional metabolic pathways for the sustainable production of valuable compounds. Firstly, new substrates including urea are identified as supporting growth of R. palustris, suggesting that it could be used to process nitrogen-rich agricultural wastes. Nitrogen runoff and pollution pose a significant environmental problem, and safe disposal represents a significant cost to industry. Using R. palustris to bioremediate these wastes, converting them to more valuable materials, would help to offset the costs of waste disposal as well as providing a sustainable source of desirable compounds. Secondly, a genetic manipulation system developed to allow the expression of heterologous genes in R. palustris is presented, and newly engineered strains of R. palustris are characterised that are capable of producing the industrially significant compound cyanophycin when R. palustris is grown on glycerol and urea. Finally, strategies are presented for the future development of R. palustris as a bioremediation system and cell-factory for sustainable biotechnology.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2020

Author dc:creator

• Hervey, John Romaine Delmar

Advisor dc:contributor.advisor

• Howe, Christopher

• Bioremediation
• photosynthesis
• waste management
• Rhodopseudomonas palustris
• glycerol
• cyanophycin
• bacterial photosynthesis
• biofuel
• biohydrogen
• bioenergy

Statement dc:rights

• Figure 1.1 on page 27 is reproduced from Gupta, R. S. (2000). The phylogeny of proteobacteria: relationships to other eubacterial phyla and eukaryotes. FEMS Microbiology Reviews 24, 367–402 with full attribution in the text and bibliography. Permission from Oxford University Press, license number 4722021043801. Figure 1.2 on page 28 is reproduced from Larimer, F. W., P. Chain, L. Hauser, J. Lamerdin, S. Malfatti, L. Do, M. L. Land, D. a. Pelletier, J. T. Beatty, A. S. Lang, F. R. Tabita, J. L. Gibson, T. E. Hanson, C. Bobst, J. L. T. Y. Torres, C. M. Peres, F. H. Harrison, J. Gibson and C. S. Harwood (2004). Complete genome sequence of the metabolically versatile photosynthetic bacterium Rhodopseudomonas palustris. Nature Biotechnology 22, 55–61 with full attribution in the text and bibliography. Creative Commons Attribution-Non-Commercial-Share Alike license, which permits distribution, and reproduction in any medium, provided the original author and source are credited.

Licence

• https://www.repository.cam.ac.uk/bitstreams/f757c3af-31d2-4d6b-97cc-4db0dd7e846f/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

en

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.46615

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/299542