High Regioselectivity Production of 5-Cyanovaleramide from Adiponitrile by a Novel Nitrile Hydratase Derived from Rhodococcus erythropolis CCM2595.

5-Cyanovaleramide (5-CVAM) is an important intermediate of a herbicide and chemical raw material. Herein, we found a novel nitrile hydratase from the strain Rhodococcus erythropolis CCM2595, exhibiting high regioselectivity with higher substrate specificity toward dinitriles than mononitriles. In the past, the strain was shown to degrade only phenol, hydroxybenzoate, p-chlorophenol, aniline, and other aromatic compounds. In our study, 20 mM adiponitrile was completely consumed within 10 min with 95% selectivity to 5-CVAM and 5% selectivity to adipamide. In addition to its high regioselectivity, our recombinant Escherichia coli showed a higher substrate tolerance of up to 200 mM adiponitrile even after 3 h when compared with two reported strains with their cyano-tolerance concentrations of up to 100 mM, which is considered to be the highest cyano-tolerance. Such a robust biocatalyst is a desirable attribute of a biocatalyst intended for use in commercial applications of 5-CVAM.