Stability study on the nitrile hydratase of Nocardia sp. 108: From resting cells to crude enzyme preparation

In recent years, nitrile hydratases (NHases) have drawn increasing attentions due to their critical roles in organic synthesis. In present paper, extensive investigation on the stability and activity of the NHase from Nocardia sp. 108, which is succeed in the industrial application in China, were conducted by the bioconversion of acrylonitrile to acrylamide in a batch manner. Cultivation study demonstrated that biosynthesis of NHase changed significantly with culture time, and the optimal NHase biosynthesis phase was 45 h after inoculation with NHase activity of 1209.8 U/g of biomass. Stability study indicated that crude enzyme preparation both exhibit a good stability when exposed to the pH 7.2 tris-HCl buffer at 4 degrees C for 4 h.