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Title: Optimisation of microbial function for the manufacture of bio-fuels from agricultural, domestic and industrial waste materials
Author: Bell, Andrew Norman William
ISNI:       0000 0004 5369 1124
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2014
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In industrial fermentation processes, alcohols accumulate and become a limiting factor to their own production through metabolic rate limitation leading to reduction of overall yield. Fermentation efficiency is reduced directly by the action of alcohols through disruption of cellular macromolecular structures. This reduces a cell's ability to undergo life processes, leading inexorably to cell death. In order to offset this ethanol-induced stress, cells produce a diverse range of stress protectants (compatible solutes). These have proven to reduce macromolecular disruption, even from agents with chaotropic modes of action and, thus, aid overall cellular stabilisation. A library of yeast species and strains was constructed to allow the identification of uniquely tolerant or intolerant stress resistance patterns, in the presence of diverse stressors. After selecting yeasts that ' proved most capable of survival across a range of stress conditions, their intracellular polyols were identified and quantified. Beta-Galactosidase, was used as a single component enzyme model system. This allowed analysis of the effects that aliphatic alcohols, compatible solutes and a combination thereof, had on the kinetic parameters of the enzyme. Whole cell stress effects were similarly examined to determine the impact of compatible solute supplementation at biologically relevant concentrations on cell growth and fermentation ability. Polyols were found to partially restore enzyme kinetic parameters and cellular growth rate during alcohol-induced inhibition. At moderate, intracellularly relevant concentrations they compounded the problem. Ultimately there were indications that some compatible solutes may be useful at low concentrations during later stages of fermentation. This thesis provides some of the basic information to enable further work in establishing appropriate supplementation procedures and the economic benefits (if any) thereof.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available