Wacker Chemie Ag

Andreas Boehm

Maria Leute

The invention relates to a method for producing a purified solution containing L-cysteine from a fermentation broth containing L-cysteine. In said method, the fermentation broth containing L-cysteine, at a pH value from pH 6 to 9, is brought in contact with a basic anion exchanger, wherein the L-cysteine bonds to the anion exchanger. The anion exchanger is then rinsed with a first washing solution, and the bonded L-cysteine is removed from the anion exchanger by means of an acid and transferred into an eluate. Said eluate, having a pH&#x2266;4, is brought in contact with an acidic cation exchanger, wherein the L-cysteine bonds to the cation exchanger. The cation exchanger is rinsed with a second washing solution, and the bonded L-cysteine is removed from the cation exchanger by means of a strong acid.

Method for purifying L-cysteine

L-cysteine-is separated from an L-cysteine-containing fermenter broth containing an oxidizing agent which is capable of oxidizing L-cysteine at pH&#x3c;5, by contacting the L-cysteine-containing fermenter broth with an ion exchanger at a pH from 5 to 9, the pH in the fermenter broth becoming &#x3c;5, and preferably &#x3c;2. The L-cysteine binds to the ion exchanger and the bound L-cysteine is then removed from the ion exchanger by means of an eluant.

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Munich, Germany

Andreas Boehm