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Title: Use of porous silicone rubber as a durable matrix for immobilizing yeast cells
Author: Perry, S. R.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1998
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The objective of this project is to investigate the potential of a novel porous silicone rubber matrix material to immobilize microbial cells, in this case the yeast, Saccharomyces cerevisiae, NCYC 1026, so that the resulting man-made immobilized cell particles with a thin disc geometry (10mm diameter by 1mm thick) can be used at high immobilized biomass loadings in conventional stirred tank vessels without any modifications. The free yeast cell liquid phase, the naturally immobilized yeast films on submerged surface solid phase and the man-made immobilized yeast cell porous silicone rubber discs solid phase were aerobically cultured in a Chemically Defined Liquid Medium with glucose as the limiting substrate at pH 4.5 and 25oC in both a batch stirred tank fermenter, a continuous stirred tank fermenter, and a complex continuous stirred tank bioreactor. The kinetic state of the free cell biomass hold-up was measured independently of the yeast in the continuous bioreaction systems, such that, these kinetic data, along with on-line substrate, biomass and dilution rate data were available for the analysis of the experimental continuous bioreaction system, using mathematical models presented and developed in this work. Mathematical modelling of batch and continuous free and immobilized cell bioreaction systems, with the additional complication of a solid phase mass transfer limited immobilized biomass hold-up resulted in complex design performance equations for the continuous bioreactors, such equations can be compared and assessed on a universal dimensionless plot of bioreactor performance, whilst the dilution rate predictor model was shown to be more useful for investigating experimental bioreactors. The immobilizing matrix material was found to enhance yeast cell growth, stabilize substrate uptake kinetics by protecting the cells from changes in the external liquid phase culture environment. The porous silicone rubber is therefore a durable and biocompatible immobilizing matrix.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available