Enzymatic Synthesis of a Key Intermediate for Rosuvastatin by Nitrilase‐Catalyzed Hydrolysis of Ethyl ( R )‐4‐Cyano‐3‐hydroxybutyate at High Substrate Concentration

An enzymatic method for the synthesis of ethyl ( R )‐3‐hydroxyglutarate from ethyl ( R )‐4‐cyano‐3‐hydroxybutyate was developed by using free and immobilized recombinant Escherichia coli BL21(DE3)pLysS harboring a nitrilase gene from Arabidopsis thaliana (AtNIT2). The hydrolysis of ethyl ( R )‐4‐cyano‐3‐hydroxybutyate proceeded with the freely suspended cells of the biocatalyst under the optimized conditions of 1.5 mol L −1 (235.5 g L −1 ) substrate concentration and 6.0 wt % loading of wet cells at pH 8.0 and 25 °C, with 100 % conversion obtained in 4.5 h. Furthermore, immobilization of the whole cells enhanced their substrate tolerance, stability, and reusability. Under the optimized conditions (100 mmol L −1 tris(hydroxymethyl)aminomethane hydrochloride buffer, pH 8.0, 25 °C), the immobilized biocatalyst could be reused for up to 16 batches, with a biocatalyst productivity of 55.6 g g wet cells −1 and a space‐time productivity of 625.5 g L −1  d −1 . These results demonstrated that the immobilized whole cells might be used as a biocatalyst in the industrial production of ethyl ( R )‐3‐hydroxyglutarate, a key intermediate for the synthesis of rosuvastatin.