Increasing the Oxygen Mass Transfer in Bioprocess Systems

The use of fermentation systems as a means of producing high commodity products at an industrial level has occurred since the mid 1930’s, most of them being anaerobic systems. The most common products produced were primary metabloites (such as ethanol, glycerol) and other such products. Modern fermentation systems however produce a lot more complex products such as secondary metoblites (such as anitbiotics) made from gentically modified organisms, to insulin production by Escherichia coli. Most modern fermentation systems are aerobic in nature, all have the problem that the oxygen mass transfer is diffusion limited and insufficent to sustain a high growth rate of the microbial community.

Some of the methods used in the Chemical Process Industry to increase the oxygen mass transfer in a reactor have included raising the reactor temperature, and also increasing the rate of agitation. However in a bioprocess some of these methods can not be used to increase oxygen mass transfer as the microbe is sensititive to the slight changes in the parameter, or the microbe becomes damaged or destroyed as a result of the change, which obviously has a negative impact on the system.

The aim of the project is to look at various different methods of increasing the oxygen mass transfer within a fermentation system. Preliminiary experiments will focus on increasing the overall volumetric mass coefficent (KLa) in an air-water system before going on to look at a simple fermentation system using either E.coli or the yeast Sacchromyces cerevisiae using a lab scale BioFlow III ™ fermenter (shown below). The ultimate aim of this project is to develop and test a centrifugal field packed bed reactor for mass transfer and productivity enhancement in fermentation systems. 

For more information please contact Dr Kamelia Boodhoo or Prof Jarka Glassey.