The invention relates to a process for the fermentative preparation of sulphur-containing amino acids chosen from the group of L-methionine, L-cysteine, L-cystine, L-homocysteine and L-homocystine, comprising the steps: a) provision of a microorganism of the family Enterobacteriaceae or of a microorganism of the family Corynebacteriaceae which has an increased thiosulphate sulphurtransferase activity compared with the particular starting strain; b) fermentation of the microorganism, from a) in a medium which contains an inorganic source of sulphur chosen from the group of salt of dithiosulphuric acid or a mixture of a salt, of dithiosulphuric acid and a salt of sulphuric acid, a fermentation broth being obtained, and c) concentration of the sulphur-containing amino acid in the fermentation broth from b).