USE OF CHEMOSTAT DATA FOR MODELING EXTRACELLULAR INULINASE PRODUCTIONBY KLUYVEROMYCES-MARXIANUS IN A HIGH-CELL-DENSITY FED-BATCH PROCESS

Production of extracellular inulinase by low-cell-density (2 kg dry we ight.m(-3)) sucrose-limited chemostat cultures of Kluyveromyces marxia nus obeyed saturated kinetics at dilution rates ranging from 0.02 to 0 .5 h(-1). A non-structured Monod-type equation, describing the relatio n between specific growth rate and specific extracellular-inulinase pr oduction rate, was used to fit experimental data. This equation was su bsequently incorporated in a model for the production of biomass and e xtracellular inulinase in a high-cell-density (> 100 kg dry weight.m(- 3)) fed-batch culture of K. marxianus grown on sucrose. The model adeq uately described biomass production in the fed-batch culture. However, the production of extracellular inulinase in the fed-batch process wa s slightly higher than predicted by the model. This observation may be related to differences in growth conditions between in the chemostat and fed-batch cultures.