摘要
为了提高产腈水合酶的菌体Nocardia sp.对催化产物丙烯酰胺的耐受性,利用极端条件改造了现有的丙烯酰胺生产菌株RS,通过向发酵液间歇加入丙烯腈催化生成丙烯酰胺,为菌体制造出一个极端环境,使菌体在生长催化过程中逐渐适应高浓度丙烯酰胺,强化其丙烯酰胺耐受性,驯化得到了RS-1菌株.研究了驯化过程中菌体存活率、比死亡速率和腈水合酶活性随丙烯酰胺浓度的变化.在不同的丙烯酰胺初始浓度(0～400g/L)下比较了两菌株的丙烯酰胺耐受性,RS-1菌体催化丙烯腈水合的速率都大于RS菌体,平均提高30.8%;而且RS-1菌株的胞内腈水合酶也具有较好的丙烯酰胺耐受性.在相同的水合条件下,RS-1菌株催化所得的丙烯酰胺终浓度和丙烯腈转化率分别为587.1g/L和99.97%,都明显优于RS菌株的水合结果.在进一步的水合实验中,RS-1菌株催化所得的丙烯酰胺终浓度达到了641.4g/L.
The RS strain, Nocardia sp., was screened at extreme cultivation conditions to improve the acrylamide- tolerance of nitrile hydratase. Arylonitrile was fed periodically into the shaker containing the RS cells and medium to produce acrylamide by the cells. The extreme cultivation conditions were formed by gradual accumulation of acrylamide. The acrylamide-tolerance of cells was enhanced in the coupling process of cell growth, enzymatic catalysis and screening. The survival rate, specific death rate and nitrile hydratase activity of cells as the function of acrylamide concentration during the process were investigated. The amount of living cells decreased rapidly with the increase of acrylamide concentration and the survival cells were cultivated on solid medium to gain a new strain RS-1. The average reaction rate of acrylonitrile hydration catalyzed by the RS-1 cells was 30.8% higher than that by the RS cells within 0~400 g/L of acrylamide concentration. Accordingly, the acrylamide-tolerance of nitrile hydratase in the RS-1 cells was superior to that in RS cells. Under the same conditions, the hydration processes catalyzed by the RS and the RS-1 strain were compared. The final acrylamide concentration and percent conversion of acrylonitrile in the hydration catalyzed by the RS-1 strain were 587.1 g/L and 99.97% respectively, which were higher than those by the RS strain significantly. In the further study on acrylamide production catalyzed by the RS-1 strain, the final acrylamide concentration reached 641.4 g/L.
出处
《过程工程学报》
EI
CAS
CSCD
北大核心
2004年第3期250-255,共6页
The Chinese Journal of Process Engineering
