Aquatic plants as whole-cell biocatalysts for preparing optically active β-hydroxy esters

Abstract

We investigated the asymmetric reduction of β-keto esters using aquatic plants as whole-cell biocatalysts under darkness and illumination by fluorescent light. The (S)- β-hydroxy esters were obtained with high enantiomeric excess (ee) values. Regardless of the light conditions, the amount of (R)- β-hydroxy ester produced did not change significantly as the substrate concentration increased, whereas the yield of (S)- β-hydroxy ester increased substantially. Moreover, increasing the quantity of plants resulted in a significant increase in the production of (S)- β-hydroxy ester and a slight increase in the production of (R)- β-hydroxy ester, reducing the ee value. The reaction proceeded more efficiently for substrates bearing bulkier ester moieties, of which the tert-butyl ester gave the best results. Ultimately, we concluded that aquatic plants can be used as whole-cell biocatalysts for preparing optically active β-hydroxy esters. This result represents a new use of aquatic plants and contributes to the achievement of carbon neutrality.