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The physiology of lactic acid production by Lactobacillus delbreuckii in a cell recycle fermenter

Major, Nicholas Charles (1987) The physiology of lactic acid production by Lactobacillus delbreuckii in a cell recycle fermenter. Doctor of Philosophy (PhD) thesis, University of Kent. (doi:10.22024/UniKent/01.02.86260) (KAR id:86260)

Language: English

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The physiology of lactic acid production by Lactobacillus deZbreuckii NRRL B-445 in a continuous fermenter with partial cell recycle has been studied and compared with that observed in a conventional chemostat .Increased formation of ethanol and acetate occurred in the recycle fermenter although lactic acid remained the major product. The yield of lactic acid from biomass and the molar product ratio, lactate: ethanol + acetate, decreased with increasing recycle ratio. The volumetric productivity of lactic acid was enhanced in the recycle fermenter due to the complete utilization of glucose, the greatest productivity (12.1 Gl 1 h-1 at D=0.3 h-1) being achieved using the lowest recycle ratio (0.5). The change in product profile was phenotypic in nature and due to glucose limitation. The specific activity of lactate dehydrogenase and the specific rate of ATP formation were maintained during cell recycle fermentation. The cellular content of polysaccharide, protein, carbon and nitrogen also remained constant and culture viability was maintained. The biomass growth yield was reduced with increasing recycle ratio. A simple mathematical model was derived which described the biomass concentration produced in the recycle fermenter at steady state over a five-fold range of concentrating effect. The derived model included a constant specific rate of glucose consumption for non-anabolic (e. g. maintenance) functions. The results suggest that catabolism and anabolism were less closely coupled in the cell recycle fermenter than in the conventional chemostrat.

Item Type: Thesis (Doctor of Philosophy (PhD))
DOI/Identification number: 10.22024/UniKent/01.02.86260
Additional information: This thesis has been digitised by EThOS, the British Library digitisation service, for purposes of preservation and dissemination. It was uploaded to KAR on 09 February 2021 in order to hold its content and record within University of Kent systems. It is available Open Access using a Creative Commons Attribution, Non-commercial, No Derivatives ( licence so that the thesis and its author, can benefit from opportunities for increased readership and citation. This was done in line with University of Kent policies ( If you feel that your rights are compromised by open access to this thesis, or if you would like more information about its availability, please contact us at and we will seriously consider your claim under the terms of our Take-Down Policy (
Uncontrolled keywords: Fermenter lactic acid process
Subjects: Q Science > QR Microbiology
Divisions: Divisions > Division of Natural Sciences > Biosciences
SWORD Depositor: SWORD Copy
Depositing User: SWORD Copy
Date Deposited: 29 Oct 2019 16:38 UTC
Last Modified: 14 Feb 2022 11:47 UTC
Resource URI: (The current URI for this page, for reference purposes)
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