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Title: Optimising solvent production in Clostridium saccharoperbutylacetonicum N1-4(HMT)
Author: Monaghan, Taylor Ian
Awarding Body: University of Kent
Current Institution: University of Kent
Date of Award: 2019
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Abstract:
The ever-increasing population and resource demand are putting a stress upon the planet's resources. This increased demand places an even greater need today for the exploration of alternative, greener fuels that can aid in the alleviation of the traditionally used fossil fuels. One such method is in the production of acetone, butanol and ethanol (ABE) by the bacteria genus Clostridium spp. These gram-positive anaerobic bacteria were first characterised in the late 19th centaury and have been used throughout the 20th and 21st centauries for their solvent producing capability, most notably in the supply of weapons grade acetone during the first world war. After falling out of favour in the last half of the 20th century due to competition with cheaper and more readily available petrochemicals; interest in ABE production via Clostridium spp. has been on the rise in recent years as the ABE fermentation is investigated for its potential as a greener more renewable source of fuel production. As interest in ABE fermentation has been on the rise in recent years, so too has our understanding of the genus as a whole. Traditionally C. Acetobutylicum first described by Chaim Weizmann in the early 20th centaury has been the industrial strain of choice. However, as the overall understanding of the strains has improved other strains have been explored for their industrial relevance. These are largely split into two characterisations, autotrophs who are able to fix CO2 and CO, converting them acetyl-CoA for solvent production and heterotrophs who are able to metabolise hexose sugars in solvent production. The strain used in this study is Clostridium saccharoperbutylacetonicum N1-4(HMT). Clostridium saccharoperbutylacetonicum N1-4(HMT) is a heterotrophic Clostridium species first described by (Hongo and Ogata, 1969) . Herein we have utilised CLEAVEÔ, this is a CRISPR/Cas system developed by Green biologics ltd. CLEAVEÔ was used for the deletion of the gene gapN from the genome of Clostridium saccharoperbutylacetonicum N1-4(HMT). GapN is a cytosolic nonphosphorylating NADP-dependant GAPDH that catalyses the irreversible oxidation of glyceraldehye-3-phospate (G3P) to 3-phospholycerate. Deletion of gapN causes a reduction in acid production, an increased rate of solvent production to pre-toxic concentrations, as well as an increase in ATP and ratio of NADH:NAD+. Additionally, the deletion of gapN results in an increase in formic and lactic acid production that is believed to be as a result of pyruvate accumulation in response to the earlier shift into solventogenesis in gapN deletion strain.
Supervisor: Shepherd, Mark Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.806683  DOI: Not available
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