Immobilization Carrier Selection And Composite Vector For The Nitrile Hydratase Cell

Immobilized cell technology, which developed from immobilized enzyme technology, is the basis of a high and new technology and methods. The cell can improve production efficiency and capacity, extend the production cycle and ease of cell separation and recovery. It also has been widely used in food industry, light chemical industry, pharmaceutical industry, the fermentation industry and waste treatment industry. The paper used immobilized cell technology and select suitable carrier to immobilize Rhodococcus sp.HUST-3, which is a nitrile hydratase producing strain and can catalyze acrylonitrile to acrylamide,to resolve at this stage of production that exist in a serious loss of enzyme activity, the process complex, post-processing requirements of the higher questions.First, nitrile hydratase producing strain Rhodococcus sp. HUST-3 was immobilized by sodium alginate, polyvinyl alcohol, polyacrylamide,chitosan and agar,and optimize the reaction conditions. The study found the relative enzyme activity of the five kind of immobilize cells was 68.3%, 62.3%, 60.7%, 82.9% and 55.5%. It also found agar is not suitable fixed the strain,but sodium alginate, polyvinyl alcohol, polyacrylamide, chitosan have their own advantages: SA immobilized cells prepared easily, PVA immobilized cells compated good, PAM immobilized cells have the highest intensity, CA immobilized cells have the highest enzyme activity. So they can be used composed.Second, orthogonal experiment and the determination nature was used on SA immobilized cells. The study found the extent of impact was: concentration of sodium alginate>volume ratio of sodium alginate and nitrile hydratase suspension>concentration of CaCl2. It also found that the best immobilized time was 6 hours, the best acrylonitrile concentration was 40g/L, the best reaction pH was 7.0,the best reaction temperature was 28℃.Third, sodium alginate was used for the basic carrier, polyvinyl alcohol, polyacrylamide and chitosan was mixed used. The study found the relative enzyme activity of the three kind of mixed immobilize cells was 93.1%, 92.7% and 97.6%. Results indicated that the best carrier was alginate-chitosan,and methods was:mix 3.5% sodium alginate and 1g/L nitrile hydratase suspension by volume ratio of 20:1, put into 4% CaCl2,and can get SA immobilized cells.Then put the cells into 1.6% chitosan-acetic acid for 30 minutes, and get ACA immobilized cells. This method producted easily,and stuff was cheap. And the cells have high mechanical strength, and relatively enzyme activity was 91.6%,which was 23.3 percentage points higher than SA immobilized cells. At the same time, ACA immobilized cells can be used for 12 times.