Production of (R)-3-Quinuclidinol by E. coli Biocatalysts Possessing NADH-Dependent 3-Quinuclidinone Reductase (QNR or bacC) from Microbacterium luteolum and Leifsonia Alcohol Dehydrogenase (LSADH)

We found two NADH-dependent reductases (QNR and bacC) in Microbacterium luteolum JCM 9174 (M. luteolum JCM 9174) that can reduce 3-quinuclidinone to optically pure (R)-(?)-3-quinuclidinol. Alcohol dehydrogenase from Leifsonia sp. (LSADH) was combined with these reductases to regenerate NAD⁺ to NADH in situ in the presence of 2-propanol as a hydrogen donor. The reductase and LSADH genes were efficiently expressed in E. coli cells. A number of constructed E. coli biocatalysts (intact or immobilized) were applied to the resting cell reaction and optimized. Under the optimized conditions, (R)-(?)-3-quinuclidinol was synthesized from 3-quinuclidinone (15% w/v, 939 mM) giving a conversion yield of 100% for immobilized QNR. The optical purity of the (R)-(?)-3-quinuclidinol produced by the enzymatic reactions was >99.9%. Thus, E. coli biocatalysis should be useful for the practical production of the pharmaceutically important intermediate, (R)-(?)-3-quinuclidinol.