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In batch bioreactor fermentations for cyclosporin A (CyA) production, good potential for bioprocess improvement was demonstrated in the immobilized cell system, providing appreciably better utilization of the catalytic activity of the biomass than the freely suspended cells, especially during the exponential phase. When concentrated nutrient medium was added pulsely during the exponential phase of cell growth (at hour 139 of fermentation), reactivation and regermination in both immobilized and suspended cell cultrues were observed to contribute to the longevity of CyA production, maintaining ncixinnuin CyA titre until 250 hours of fermentation. Contrarily, simple batch fermentations without any supplement of medium in both systems showed repid decrease in CyA concentrations during the late stationary phase. Notably, the CyA yield coefficient( Y7,) for the immobilized cell system was maintained quite high even after the pulse addition of the concentrated full medium, reaching almost 80% of the level attained during the exponential phase. This is in sharp contrast when compared with the corresponding value of 58% in the case of parallel suspended cells. This pattern of CyA production resulted in considerably enhanced CyA production in the immobilized cell system, reaching almost 2 tinxs higher maximum CyA production in comparison with the free cell system.
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