Bioprospecting for Microorganisms and Enzymes with Biorefining Potential

Student thesis: Doctoral ThesisDoctor of Philosophy


The rise of biorefining and application of biotechnology to combat climate change and accomplish energy security is a necessity. There have already been steps to produce sustainable biofuels and products throughout the world. However, not all processes are economically viable due to costs of enzymes, pre-treatments, and scale-ups. In this project Miscanthus sp. was the main source of bacterial isolation due to its bioenergy characteristics as a low-input high-output crop. Specifically, due to the high sugar content of harvested senesced Miscanthus. The aim of this project was to discover novel microbes and enzymes with potential to contribute to the generation of fuels and chemicals from plant biomass. Specifically, we aimed to isolate and characterise enzymes capable of efficiently releasing sugars from pre-treated lignocellulosic biomass, for subsequent fermentation to ethanol and platform chemicals. Aerobic bacteria were cultured from harvested chipped Miscanthus and soil surrounding Miscanthus crops and were characterised morphologically, functionally and taxonomically. Bacteria in our collection included amongst others: Pseudomonas sp., Burkholderia sp., Variovorax paradoxus, Luteibacter sp. and Bacillus sp.. The collection was screened for carbon utilisation using cellulose (in the form of carboxymethyl cellulose), xylan (from beechwood) and starch by enzymatic activity, at a range of temperatures and pHs. From the bacterial library, 88.5% of cultures showed cellulase activity, 93.2% xylanase activity, 79.7% starch degradation activity over the temperature or pH range, with 66.2% demonstrating activity over all three assays. Proteins were isolated from bacteria that demonstrate effective starch utilisation for further characterisation. Bacterial isolates that exhibited xylan utilisation at high pH and temperature were characterised by whole genome sequencing to identify interesting enzymes and pathways using bioinformatics software CLC genomics and Seed RAST. Finally, homologous proteins have been modelled using Phyre2 and 3DLigandSite to analyse structure and binding sites. This work was part of the wider BEACON project which aimed to establish Wales as a Biorefining Centre of Excellence. BEACON built integrated ‘Green Supply Chains’ with a focus on developing new routes to functional, cost competitive products using biomass rather than fossil fuels.
Date of Award10 Mar 2016
Original languageEnglish
Awarding Institution
  • Aberystwyth University
SupervisorKerrie Farrar (Supervisor) & Justin Pachebat (Supervisor)

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