Reaction Engineering of Benzaldehyde Lyase from Pseudomonas fluorescens Catalyzing Enantioselective C−C Bond Formation

The reaction engineering of benzaldehyde lyase (BAL, E.C. 4.1.2.38) from Pseudomonas fluorescens catalyzing the enantioselective carboligation of benzaldehyde and acetaldehyde yielding ( R )-2-hydroxy-1-phenylpropanone (HPP) is presented. Based on kinetic studies a continuous process is developed. The developed bioreactor allows focusing the complex reaction system on the production of HPP with simultaneous discrimination of the undesired benzoin formation. The application of a continuous process in combination with membrane technology enables high space time yields (1120 g L - 1 d - 1, ee > 99%) of the product as well as high total turnover numbers of the biocatalyst (mol of product/mol of biocatalyst = 188.000). A kinetic model was developed to simulate the continuously operated reactor and to determine optimal production conditions. The synthesis of ( R )-(3-chlorophenyl)-2-hydroxy-1-propanone (1214 g L - 1 d - 1, ee = 99%) in the bioreactor demonstrates a broad applicability of the presented reactor concept for the production HPP derivatives.