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Title: Biochemical studies with Escherichia coli : (I) Products of glucose metabolism during growth, (II) Mechanism of ethanol formation
Author: Foster, Shelagh M.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1956
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Abstract:
Part 1. (1) The production of metabolites during the growth of Bacterium well follows a well defined pattern. The concentration of metabolites is very low during the early, logarithmic growth phase and increases rapidly just before the onset of stationary phase. In non-proliferating cultures, subsequent to the cessation of growth, the metabolite concentrations decrease at a rate dependent on the degree of aeration, (S) In cultures of different initial pH value, but with a similar degree of aeration, the metabolites produced, when expressed as a function, of cell numbers in the culture, are the same in each culture regardless of pH. (3) The continued utilization of glucose by stationary phase cultures depends on the initial pH of the medium and is independent of the degree of aeration during growth, (4) The metabolism of glucose by cell suspensions of B. coli is affected by pH, This has previously been-shown in terms of the end products produced from the glucose, (Tikka 1935, Stokes 1949) . The raise of utilization depend on the pH s these are at a maximum at pH 7.1, and decrease as the pH is lowered. (5) The relation of these findings to the dependence of glyeolysis on the oxidation reduction of diphosphopyridine nucleotide (DPH) is discussed. (1) The ability of washed cell suspensions to produce ethanol from glucose depends on the conditions of growth. A medium, containing traces of peptone and yeast extract, and Incubated under anaerobic conditions, produces cells with the highest activity. (2) The strain of B. cell used produced 2.8 moles acid from l umole glucose. The ethanol, acetic acid ratio was approximately 1:1. The ethanol glucose ratio was approximately 0.7:1. (3) The effect of inhibitors on the production of pyruvate and ethanol from glucose gives evidence that ethanol arises from pyruvate. No evidence of a second pathway via - glycerophosphate could be obtained. (4) Ethanol production is dependent on Coenzyme A(CoA). This was shown in experiments with a pantothenate requiring mutant boll and also by the treatment of cell-free extracts of B. Coli with Dowex 1. (5) No ethanol was detected from the dissimilation of pyruvate by cell suspensions of B. Coli. (6) Ethanol is utilized by cells of B. coli. The production of ethanol from glucose tinder the standard conditions adopted reached a maximum after 60 minutes and then declined. Also ethanol on incubation with a cell suspension of B. coli under an atmosphere of is utilized. The fate of this ethanol la unknown. No relationship could be established between ethanol and acetic-acid concentrations. (7) The alcohol dehydrogenase activity of cell-free extracts of B. coli was studied. These were partially purified by (NH4.)g SO4 fractionation and by elution from a calcium phosphate gel, (6) A cell free extract, of B. coli showed slight activity for the oxidation of acetaldehyde This was dependent on CoA and (9) The extracts could not reduce acetic acid or acetyl phosphate: via acetaldehyde to ethanol. (10) These results supported the proposed pathway of ethanol production from glucose.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.777158  DOI: Not available
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