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Title: The acetone ethanol fermentation of Bacillus macerans
Author: Masduqie, Z. B.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1991
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Bacillus macerans is capable of producing, under certain conditions, acetone and ethanol by fermenting a wide variety of carbohydrates. Little work has been done to investigate the system since the first two decades of this century and the aim of this study was to assess the potential use of B.macerans for the production of solvents together with an investigation of the factors controlling solventogenesis. Typically solvents were produced after an initial acidogenic growth phase in which the acetic was formed with a concomitant drop in pH. After an initial examination of the cultural characteristcs of the organism, the study involved the investigation of the conditions of solvent production in 3 types of pH controlled fermentation system, i.e. batch, single and two-stage continuous cultures. The main theme of these investigations was to determine the influence of glucose concentration and pH on the production of solvents. The results show that good concentrations of solvents, up to 250-300 mM ethanol and 80-100 mM acetone from 5% w/v glucose, could be produced in both batch and two stage continuous systems. However the single stage continuous culture gave poor results with low carbon recoveries and lower solvent concentrations (ethanol-acetone). This was thought to be largely due to the selective pressures associated with such a system and the incompatabilities of such a system with non-growth related (secondary) end product formation. Carbon recoveries for all systems were low especially in single stage continuous cultures, where lactic acid was an additional product. It was also suspected that additional undetected non volite products are produced. The volumetric productivities of three solvent producing systems at pH 6 on 5&37 glucose were 0.253 g/h/l for ethanol and 0.083 for acetone in batch; 0.699 g/h/l for ethanol and 0.088 g/h/l for acetone in continous; 0.702 g/h/l for ethanol and 0.229 g/h/l for acetone in a two stage system.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available