Biotransformation of theobromine to caffeine in suspension and polyurethane foam immobilized coffee (Coffea arabica L.) cells.

Coffee (Coffea arabica L.) cells are capable of biotransforming theobromine to caffeine. In suspension culture of B2K medium, which is the "production medium" for caffeine, biotransformation was also more efficient than in DK medium. More caffeine was finally produced than calculated based on theobromine added to the medium. On the other hand, the efficiency of the biotransformation using immobilized cells in reticulate polyurethane foam cubes as a matrix varied with the phases. The biotransformation tended to be efficient under conditions which allowed the coffee cells to vigorously produce caffeine de novo.