Production of gibberellins and bikaverin by cells of Gibberella fujikuroi immobilized in carrageenan

The production of gibberellins and bikaverin by immobilized and free cells of Gibberella fujikuroi strains was followed. Both types of cells, free and immobilized, produced similar titers of the secondary metabolites during the normal growth cycle. The kinetics of nutrient use and product formation by the immobilized cells lagged behind that of the free cells and this was assumed to be the result of diffusional limitations imposed on the immobilized cells. A noticeable difference was that in the immobilized cells, all of the bikaverin was excreted into the medium for both strains of G. fujikuroi tested but in the free cell fermentation 44% was excreted for strain ACC 917 and only 10% for strain GF1a. Gibberellin and bikaverin could be produced in a semi-continuous fashion with both free and immobilized cells for a period of 16 d in a resuspension medium containing 0.12 mM or 0.60 mM ammonium chloride. No definite advantage, on a productivity basis, for using immobilized cells over free cells could be seen.