Selective production of l-serine derivative isomers

Abstract

L-Serine derivatives produced by the enzyme catalyzed aldol condensation of glycine and an aldehyde in aqueous solution are recovered in high yield by extracting the aqueous product solution containing said serine derivatives with an organic phase comprising (i) an aldehyde, or (ii) mixtures of an aldehyde and a water immiscible organic solvent, followed by re-extracting the organic phase with an aqueous phase having a pH of less than about 7.0. The L-erythro isomers of L-serine derivatives such as L-phenylserine may be preferentially prepared by the use of this extraction/re-extraction procedure in combination with bioreactor reaction conditions which include a pH of from about 7.5 to 10, an aldehyde concentration of from about 1 to about 90 grams/liter, a glycine concentration of from about 10 to about 300 grams/liter, and a molar ratio of glycine to aldehyde of from about 4:1 to about 100:1.