Kirk, TV; (2013) Microfluidic microbioreactor for eukaryote culture with dissolved oxygen control. Doctoral thesis , UCL (University College London).

Abstract

In this PhD project a 50µL volume oscillating jet driven microfluidic microbioreactor was developed. This system features dissolved oIn this PhD project a 50µL volume oscillating jet driven microfluidic microbioreactor was developed. This system features dissolved oxygen (DO) contIn this PhD project a 50µL volume oscillating jet driven microfluidic microbioreactor was developed. This system features dissolved oxygen (DO) control and has fulfilled several design criteria and performance goals, which were demonstrated with fermentations conducted with Saccharomyces cerevisiae in YPD media. The device’s principle of operation is novel and newly demonstrated. The oscillating jet system generates active mixing without on-chip moving parts. The system is the only in its class to demonstrate DO control with yeast, in this case the industrially and scientifically important eukaryote S. cerevisiae. This is a new and novel result. The device has the smallest volume of any actively mixed microbioreactor, and does not suffer from evaporation of water from media. Reproducibility of DO monitoring and control has been demonstrated. This was done under the standard conditions for fermentation of S. cerevisiae, and has been extended up to 30 hours in duration, and to cell densities measured by optical density (OD) of over 20cm-1. DO control was maintained up to cell densities of ~ OD 10cm-1, which corresponds to a biomass concentration of 4.7 g-dcw/L. The system was demonstrated to be robust and reliable in mechanical and fluidic function. There are indicators that the DO control system has an effect on cell metabolism, an important consideration for microbioreactors as they are ultimately intended for use as high-throughput systems for process development, metabolic engineering, and synthetic biology. The volumetric mass transfer coefficient of the system is 174hr-1, which is high for its class. This is the key parameter for determining bioreactor oxygen transfer performance and scale-up suitability. Monitoring of cell growth via OD is less consistent than desired however. This may be due to the system’s limitation in maintaining S. cerevisiae cells in suspension at higher densities. This may also limit the “real-world” oxygen transfer performancerol and has fulfilled several design criteria and performance goals, which were demonstrated with fermentations conducted with Saccharomyces cerevisiae in YPD media. The device’s principle of operation is novel and newly demonstrated. The oscillating jet system generates active mixing without on-chip moving parts. The system is the only in its class to demonstrate DO control with yeast, in this case the industrially and scientifically important eukaryote S. cerevisiae. This is a new and novel result. The device has the smallest volume of any actively mixed microbioreactor, and does not suffer from evaporation of water from media. Reproducibility of DO monitoring and control has been demonstrated. This was done under the standard conditions for fermentation of S. cerevisiae, and has been extended up to 30 hours in duration, and to cell densities measured by optical density (OD) of over 20cm-1. DO control was maintained up to cell densities of ~ OD 10cm-1, which corresponds to a biomass concentration of 4.7 g-dcw/L. The system was demonstrated to be robust and reliable in mechanical and fluidic function. There are indicators that the DO control system has an effect on cell metabolism, an important consideration for microbioreactors as they are ultimately intended for use as high-throughput systems for process development, metabolic engineering, and synthetic biology. The volumetric mass transfer coefficient of the system is 174hr-1, which is high for its class. This is the key parameter for determining bioreactor oxygen transfer performance and scale-up suitability. Monitoring of cell growth via OD is less consistent than desired however. This may be due to the system’s limitation in maintaining S. cerevisiae cells in suspension at higher densities. This may also limit the “real-world” oxygen transfer performancexygen (DO) control and has fulfilled several design criteria and performance goals, which were demonstrated with fermentations conducted with Saccharomyces cerevisiae in YPD media. The device’s principle of operation is novel and newly demonstrated. The oscillating jet system generates active mixing without on-chip moving parts. The system is the only in its class to demonstrate DO control with yeast, in this case the industrially and scientifically important eukaryote S. cerevisiae. This is a new and novel result. The device has the smallest volume of any actively mixed microbioreactor, and does not suffer from evaporation of water from media. Reproducibility of DO monitoring and control has been demonstrated. This was done under the standard conditions for fermentation of S. cerevisiae, and has been extended up to 30 hours in duration, and to cell densities measured by optical density (OD) of over 20cm-1. DO control was maintained up to cell densities of ~ OD 10cm-1, which corresponds to a biomass concentration of 4.7 g-dcw/L. The system was demonstrated to be robust and reliable in mechanical and fluidic function. There are indicators that the DO control system has an effect on cell metabolism, an important consideration for microbioreactors as they are ultimately intended for use as high-throughput systems for process development, metabolic engineering, and synthetic biology. The volumetric mass transfer coefficient of the system is 174hr-1, which is high for its class. This is the key parameter for determining bioreactor oxygen transfer performance and scale-up suitability. Monitoring of cell growth via OD is less consistent than desired however. This may be due to the system’s limitation in maintaining S. cerevisiae cells in suspension at higher densities. This may also limit the “real-world” oxygen transfer performance

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