KINETICS OF GROWTH AND RIBOSOME-INACTIVATING PROTEIN-PRODUCTION FROM TRICHOSANTHES KIRILOWII PLANT-CELL CULTURES IN A 5-L BIOREACTOR

Ribosome-inactivating proteins, named for their ability to inhibit pro tein translation in cell-free systems, are an important class of natur al plant defense proteins with potential human therapeutic and agricul tural applications. The kinetics of growth, nutrient consumption, and extracellular protein translation inhibitory activity are presented fo r Trichosanthes kirilowii plant cell suspensions in 5-L bioreactors at two agitation rates (50 and 100 rpm). The cultures had a 7-9.5 day la g phase followed by exponential growth with a doubling time of less th an 2 days. Biomass concentrations reached levels of approximately 19 g (dry weight)/L. Protein translation inhibitory activity was observed in the culture broths during the exponential growth phase and reached levels of approximately 50-60 units. No detrimental effects of agitati on were observed at 100 rpm. These studies demonstrate the potential f or plant cell culture production of ribosome-inactivating proteins in bioreactor systems.