Microbial Production of Chiral Hydroxy Esters and Their Analogs: Biocatalytic Reduction of Carbonyl Compounds by Actinobacteria, Agromyces and Gordonia Strains

We screened 15 Agromyces strains from the Microbacteriaceae family and 16 Gordonia strains from the Gordoniaceae family to investigate their biocatalytic ability to reduce carbonyl compounds. Two Agromyces strains (A. soli NBRC109063 and A. humatus NBRC109085) and two Gordonia strains (G. hydrophobica NBRC16057 and G. malaquae NBRC108250) grew well in 230 medium. The stereoselective reduction of various carbonyl compounds using these four strains was investigated. We discovered that these strains can reduce aliphatic and aromatic α-keto esters and an aromatic α-keto amide. On the basis of the conversion rate and stereoselectivity of the alcohols produced, G. hydrophobica NBRC16057 is a potential biocatalyst for the stereoselective reduction of α-keto esters and an aromatic α-keto amide to the corresponding chiral alcohols. Our results also suggest that the reduction of ethyl 2-methylacetoacetate by wet G. hydrophobica NBRC16057 cells in the presence of L-glutamate is useful for the production of chiral ethyl 3-hydroxy-2-methylbutanoate.