SHEAR SENSITIVITY OF PLANT-CELLS IN SUSPENSIONS - PRESENT AND FUTURE

Plant cells are a source of pharmaceuticals, fragrances, flavors, and dyes that are traditionally produced by extraction of tissues from whole plants. Recent trends in plant product research, transformed cell lines, and conservation policies place increased demand on plant cell culture technology. Unlike processing of microbial and animal cells in bioreactors, no economically viable process based on the suspension culture of plant cells in bioreactors has yet been possible in North America. It is proposed that the suspended-cell bioreactor is the method of choice and that plant cells respond to fluid forces (defined as laminar shear and turbulent eddies-based and bubble-based forces) differently from their animal cell counterparts in bioreactors. Although plant cells produce a tough cell wall, fluid forces, although not lethal within normal range, impact the membrane transport processes and metabolic function of plant cells; these effects are termed sublytic. Previous approaches to shear sensitivity of plant cells are reviewed in the context of these sublytic effects. A model for systematic evaluation of fluid-mechanical causes and physiological mechanisms behind sublytic effects is proposed. It is further proposed that, once understood, the plant cell's sublytic responses to fluid force can be used advantageously in stirred suspension cultures.