| Acrylamide is an important organic chemical commodiaty, which is mainly used for producing polyacrylamde. Being used as flocculant, thickener, and enhancer, polyacrylamide is widely applied in papermaking, geological drilling, wastewater treatment, textile industry and chemical industry, and food processing etc., especially in petroleum industry. Acrylamide is hydrated by acrylonitrile as the raw material. Since 1950s the productive technology has been upgraded from chemically sulfuric hydration and cupric catalysis to the latest microbial enzymatic catalysis, which is characterized by high selectivity, activity, and retrieval rate. Nitrile hydratase is a key enzyme in the biotransformation process as a biocatalyst, which can catalyze acrylonitrile to acrylamide in a temperate condition. Therefore,the fermentation of Rhodococcus sp.SHZ-1 strain,a producer of nitrile hydratase, was optimized and its enzymologic characters in free cell suspension were studied in this paper. The results were obtained as follows:1. The results of morphological and physiological studies of SHZ-1 shown it belongs to Rhodococcus.2. The process of nitrile hydratase (NHase) produced by Rhodococcus sp. strain SHZ-1 was investigated for establishing the interrelation of cell growth, enzyme production, and effect of pH and glucose consumption on NHase activity. The higher expression of NHase activity in the ferment was studied also and shown that pH adjustment and glucose supplement during feed batch fermentation could significantly increase cell growth and NHase activity for 34.12% increment,from 5226U/ml to 7009.18U/ml.3. The highest nitrile hydratase activity level was receached at 30℃and in neutral pH solution. The influences of the substrate concentration on the enzyme activity shown that the optimal concentration of acrylonitrile was 7.2%. When the concentration of the final product acrylamide was 40%,it would inhibit the activity of nitrile hydratase strongly. |
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