An investigation of the effect of hydrodynamic stress on the growth, morphology and metabolism of microorganisms

 

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dc.contributor.advisor Harrison, STL en_ZA
dc.contributor.author Illing, Suzanne en_ZA
dc.date.accessioned 2016-05-04T12:50:36Z
dc.date.available 2016-05-04T12:50:36Z
dc.date.issued 1997 en_ZA
dc.identifier.citation Illing, S. 1997. An investigation of the effect of hydrodynamic stress on the growth, morphology and metabolism of microorganisms. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/19425
dc.description.abstract The cultivation of bacteria requires high levels of agitation and aeration to satisfy the mass transfer requirements of the cells. Associated with these conditions are turbulent forces which may act on the surfaces of the cells and be detrimental to their growth, metabolism and morphology. Reactor design and operation may require a compromise between the stress sensitivity and the mass transfer requirements of the .microbial system. In this project, the development of general predictive techniques to optimise the design and operation for stress sensitive microorganisms was sought. The effect of hydrodynamic stress on the growth, metabolism and morphology of Corynebacterium glutamicum (ATCC 13032) and Brevibacterium flavum (NRRL 114 75) was investigated in a stirred tank bioreactor in the absence of mass transfer limiting conditions. The results showed that hydrodynamic trauma had no effect on the growth and metabolism of the bacteria. Breakup of bacterial aggregates was however observed, the extent of which depended on the intensity of the hydrodynamic conditions. The extent of aggregate breakup was greater for Corynebacterium glutamicum. It was postulated that the bacteria were held together by a growth associated biomolecular adhesive. The kinetics and mechanism for Corynebacterium glutamicum aggregate breakup in the absence of a gaseous phase, were studied in a stirred tank reactor and capillary flowloop system. A model was developed to describe the rate of aggregate breakup caused by aggregate-turbulent eddy interactions in the impeller zone of the stirred tank reactor and in the wall region of the capillary, in the absence of air bubbles. It assumes that aggregate disruption is caused by the interaction with similarly sized eddies. The extent of aggregate breakup was a function of the magnitude of the turbulent force as well as the total duration of the force event. A similar model was developed to describe the rate of microbial cell death. The forces associated with turbulent eddies in the impeller zone of the stirred tank reactor were compared with those of collapsing air bubbles at the air medium interface. The results showed that both contributed to the total force acting on the cells. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Bioprocess Engineering en_ZA
dc.subject.other Chemical Engineering en_ZA
dc.title An investigation of the effect of hydrodynamic stress on the growth, morphology and metabolism of microorganisms en_ZA
dc.type Doctoral Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Engineering and the Built Environment
dc.publisher.department Centre for Bioprocess Engineering Research
dc.type.qualificationlevel Doctoral
dc.type.qualificationname PhD en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Illing, S. (1997). <i>An investigation of the effect of hydrodynamic stress on the growth, morphology and metabolism of microorganisms</i>. (Thesis). University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Bioprocess Engineering Research. Retrieved from http://hdl.handle.net/11427/19425 en_ZA
dc.identifier.chicagocitation Illing, Suzanne. <i>"An investigation of the effect of hydrodynamic stress on the growth, morphology and metabolism of microorganisms."</i> Thesis., University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Bioprocess Engineering Research, 1997. http://hdl.handle.net/11427/19425 en_ZA
dc.identifier.vancouvercitation Illing S. An investigation of the effect of hydrodynamic stress on the growth, morphology and metabolism of microorganisms. [Thesis]. University of Cape Town ,Faculty of Engineering & the Built Environment ,Centre for Bioprocess Engineering Research, 1997 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/19425 en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Illing, Suzanne AB - The cultivation of bacteria requires high levels of agitation and aeration to satisfy the mass transfer requirements of the cells. Associated with these conditions are turbulent forces which may act on the surfaces of the cells and be detrimental to their growth, metabolism and morphology. Reactor design and operation may require a compromise between the stress sensitivity and the mass transfer requirements of the .microbial system. In this project, the development of general predictive techniques to optimise the design and operation for stress sensitive microorganisms was sought. The effect of hydrodynamic stress on the growth, metabolism and morphology of Corynebacterium glutamicum (ATCC 13032) and Brevibacterium flavum (NRRL 114 75) was investigated in a stirred tank bioreactor in the absence of mass transfer limiting conditions. The results showed that hydrodynamic trauma had no effect on the growth and metabolism of the bacteria. Breakup of bacterial aggregates was however observed, the extent of which depended on the intensity of the hydrodynamic conditions. The extent of aggregate breakup was greater for Corynebacterium glutamicum. It was postulated that the bacteria were held together by a growth associated biomolecular adhesive. The kinetics and mechanism for Corynebacterium glutamicum aggregate breakup in the absence of a gaseous phase, were studied in a stirred tank reactor and capillary flowloop system. A model was developed to describe the rate of aggregate breakup caused by aggregate-turbulent eddy interactions in the impeller zone of the stirred tank reactor and in the wall region of the capillary, in the absence of air bubbles. It assumes that aggregate disruption is caused by the interaction with similarly sized eddies. The extent of aggregate breakup was a function of the magnitude of the turbulent force as well as the total duration of the force event. A similar model was developed to describe the rate of microbial cell death. The forces associated with turbulent eddies in the impeller zone of the stirred tank reactor were compared with those of collapsing air bubbles at the air medium interface. The results showed that both contributed to the total force acting on the cells. DA - 1997 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 1997 T1 - An investigation of the effect of hydrodynamic stress on the growth, morphology and metabolism of microorganisms TI - An investigation of the effect of hydrodynamic stress on the growth, morphology and metabolism of microorganisms UR - http://hdl.handle.net/11427/19425 ER - en_ZA


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