Patent ID: 7807420

Claim:
A method for producing a basic amino acid from the fermentation broth of a microorganism strain producing the basic amino acid, the method comprising: a) separating the microorganisms from the fermentation broth and b) separating the basic amino acid from the aqueous broth obtained in step a) by loading a single-stage or multistage arrangement of a strongly acidic cation exchanger in its salt form with the broth obtained in step a) and eluting the basic amino acid, wherein the aqueous broth, before the loading in step b), has a pH in the range of 4 to 7.5 and at least the first stage of the cation-exchange arrangement is pretreated with an aqueous acid in such a manner that at the end of the pretreatment, the pH at the outlet of the pretreated cation exchanger is of 4.5 to 7.