弹性蛋白酶产生菌的分离鉴定和发酵条件研究

Identifing and Screening Elastase-producing Strains and Its Fermentation Conditions

从污水河的土壤中采集样品,分离得到一株产胞外弹性蛋白酶活性较高且稳定的细菌。经初步鉴定属枯草芽孢杆菌(Bacillus subtilis B1),其酶活力为74.25U/ml。对其进行物理诱变,诱变后的菌株(B9)产酶活性有较大的提高。B9酶活力为120.00U/ml,较原菌株提高了1.62倍。同时研究了其产酶最适条件,产酶最适碳源为蔗糖,最适氮源为干酪素,并对碳源、氮源和生长因子进行了正交试验,研究发现氮源对产酶的影响最大。当蔗糖的用量为4%、干酪素为3%、玉米提取液为0.1%时具有较高的产酶水平。最适发酵初始pH为8.0、300ml最适摇瓶装量为40ml、最适接种量为3%。经发酵条件的优化后,B9酶活达到311.54U/ml、提高了2.59倍;较以往国内报道的酶活要高。

Strains capable of secreting extracellular elastase were isolated from the soil of the river. Strain No.B 1 with the highestyield elastase was identified as Bacillus subtilis. The enzyme activity was originally 74.25 U/ml. After the physical mutation the enzyme activity of strain B9 becomes 120.00 U/ml, enhanced 1.62 times higher than the original strains. Simultaneously the optimum conditions of the enzyme production were studied. The most suitable carbon source is sucrose, and nitrogen sources is casein. The orthogonal test was carried on to have discovered that the nitrogen source affected the enzyme activity highly. When the sucrose to used amounts 4% with the casein 3%, and the corn steep liqid 0.1%, the elastase production is the highest. While the optimal fermentation initial pH is pHS.0, 300 ml flask ventilation 40 ml and vaccination quantity 3%. After the fermentation conditions being optimized, the strain B9, enzyme activity is 311.54 U/ml, enhanced 2.59 times higher than the former reported enzyme activity.