Fermentation medium for increased yield of Corynebacterium diphtheriae toxin, and uses of the toxin.

The present invention relates to a fermentation medium for cultivating Corynebacterium diphtheriae. The medium is free from animal-derived components and comprises water, a nitrogen source, a carbon source and an iron supplement, wherein the culture of Corynebacterium diphtheriae in at least 100 L of fermentation medium yields at least 140 Lf/ml of diphtheria toxin. The exemplified source of nitrogen is yeast extract, and the exemplified carbon sourceis maltose. The invention also relates to the use of the fermentation medium in processes for obtaining diphtheria toxin from the Colynebacterium diphtheriae bacteria being cultivated and the preparation of vaccines using the diphtheria toxin obtained in the processes. The present invention further relates to a purification and detoxification processes specifically adapted for preparing a diphtheria toxoid for inclusion into a vaccine.