Towards a fundamental understanding of the polyethylene and polyethylene terephthalate degradation in Streptomyces sp.
Publication Date
July 18, 2023
Creator
Abstract
Plastic is essential to modern society, driven primarily by its incredible versatility as a material coupled with its low production costs. However, this utility has come at a significant environmental cost, given 8.3 billion tonnes of plastic waste have been generated globally since the 1950s. A third of all plastics end up in the environment with 165 million tons/year ending up in the oceans, creating vast accumulations of life-choking rubbish. As recently highlighted in Blue Planet, plastic accumulation in the oceans has devastating consequences for marine life, with nearly 700 different species affected by plastics every year. Oil-based plastics are being produced at a rate exceeding 330 million tons per annum. Plastics were originally developed for performance, with little consideration given to the environmental impact. However, the enormity of the multi-tiered (behavioural, lack of recycling etc.) plastic problem is now very apparent and a sustainable solution to the plastic problem is urgently required. The crux of the problem lies with the molecular nature of the materials, which makes them difficult to degrade. Although some plastics can be recycled this is a finite process, with many eventually ending up in landfill.
Several studies have already identified several microorganisms that can utilize plastics as "food." Although these studies have addressed some aspects of how the bacteria degrade the plastic there are still several unknowns which need to be addressed. Recent research has started to address how bacteria degrade plastics but in-depth knowledge on pathways and enzymes is still missing for most plastics. Furthermore, previous reports have described the degradation of chemical additives, without detailing the specific degradation of the polymer. This thesis aimed to provide a comprehensive understanding of the metabolic and enzymatic degradation of virgin polyethylene terephthalate (PET) and polyethylene (PE) by Streptomyces sp. F. A novel Streptomyces sp. isolated from soil and previously shown to degrade commercial PET and PE. Growth was confirmed on both PET and PE utilising a combination of colony forming units, metabolomics and transcriptomic analysis. Significant differences were seen in the both the metabolite and transcriptomic profile when the cells were grown on both PET and PE. Finally, the genome was sequenced enabling bioinformatics analysis of predicted pathways for both PE and PET degradation. This research has identified a strain which can grow on two different plastics, the first time this has been reported and is a first step towards understanding the degradation process for PE and PET in a Streptomyces.
Item Type
ethesis
Thesis Type
PhD
Supervisors
Subjects (LC)
Associated Schools / Departments
School of Life Sciences
eprints ID
73425
UoN Repository URI
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