A dynamic combinatorial screen for novel imine reductase activity

New imine reductase activity has been discovered in the anaerobic bacterium Acetobacterium woodii by screening a dynamic combinatorial library of virtual imine substrates, using a biphasic water–tetradecane solvent system. Benzylidine aniline and butylidine aniline were reduced to the corresponding amines by caffeate-induced cells, whereas uninduced cells reduced butylidine aniline only. The reductions were detected despite side reactions that consumed some of the starting materials. The new screen can now be extended to discover synthetically useful imine reductases and enzymes that catalyse reactions for which biocatalytic equivalents of the chemical reactions have not yet been discovered.