Preparation of CLEAs of a recombinant NHase ES-NHT-118

Preparation of Cross-linked Enzyme Aggregates of Nitrile Hydratase ES-NHT-118 from E. coli by Macromolecular Cross-linking Agent

Liya Zhou, Haixia Mou, Jing Gao, Li Ma, Ying He and Yanjun Jiang

Chinese Journal of Chemical Engineering (in press)

http://dx.doi.org/10.1016/j.cjche.2016.08.027

Cross-linked enzyme aggregates (CLEAs) of nitrile hydratase (NHase) ES-NHT-118 from E. coli were prepared by using ammonium sulfate as precipitating agent followed by cross-linking with dextran polyaldehyde for the first time. In this process, egg white was added as an amine source to aid formation of CLEAs. The optimal conditions of the immobilization process were determined. Michaelis constants (K_m) of free NHase and NHase CLEAs were also determined. The NHase CLEAs exhibited increased stability at varied pH and temperature conditions compared to its free counterpart. When exposed to high concentrations of acrylamide, NHase CLEAs also exhibited effective catalytic activity.

 

NHase expression in Corynebacterium glutamicum

Industrial scale biocatalytic production of acrylamide relies on the use of engineered strains of Rhodococcus. There is a newly accepted manuscript in Applied Microbiology and Biotechnology from three Korean groups lead by J-H Lee and H-S Kim where the NHase from a Rhodococcus strain is expressed in Corynebacterium glutamicum (a cell factory already used commercially in amino acid biosynthesis) and tested for its ability to hydrate acrylonitrile. Whilst it didnt have the same activity as the NHase in the homologous system, the advantage the authors propose is that the rate of growth and hence enzyme production is higher with C. glutamicum.