Oxygen Transport In Plant Tissue Culture Systems

Abstract

The principles of oxygen mass transfer are presented to provide a qualitative understanding of the culture conditions where oxygen transport limitations can be observed. The context of the discussion is the applications of these principles to plant tissue culture propagation vessels and bioreactors. An experimental system which effectively uses an inhibitory protein driven by alcohol-inducible promoter is used as a qualitative probe of oxygen deprivation in the germinating seeds. Oxygen limitation is correctly predicted in this system even when the consumption rates of the seeds are extremely small as compared to the gas-liquid oxygen transfer rates. It is shown that the solid-liquid boundary layer is far more constraining for the delivery of oxygen. Use of oxygen enrichment of the gas phase overcomes this mass transfer limitation by increasing the driving force for transport in the bulk liquid phase. These principles of oxygen mass transfer can be adapted (both qualitatively and quantitatively) to many other aspects of oxygen-limited growth of plant tissues in culture.