耐高温α-淀粉酶产生菌的分离鉴定及发酵条件与酶性质研究

The Screening of a Thermostable α-Amylase-producing Strain and the Study on It's Properties

从西藏八宿温泉附近土壤中 ,分离到一株能在 5 .5℃生长并分泌高温α- 淀粉酶的菌株 ,其生长pH 5 . 0～11. 0 ,最适生长pH 7. 0～ 8. 0。该菌株经初步鉴定为地衣芽孢杆菌 ,命名为BacilluslicheniformisZ - 8。在 4 5℃ ,10 %装液量 ,16. 0r/min条件下振荡培养 4 8h后 ,发酵液酶活可达 2 1. 2× 10 .4UV/mL。发酵培养基的组成成分为黄豆粉 0 . 5 %、麸皮 1%、可溶性淀粉 0 . 2 5 %、pH 8. 8。对该酶的性质研究表明 ,其最适作用pH为 6 . 0 ,最适反应温度为 95℃ ,95℃下保温 6 0min处理后酶活仅损失 5 . 4 % ,对Ca2 + 没有依赖性。

An thermostable α-amylase-producing strain,thermophilic Bacillus licheniformis Z-8,was isolated from a spa soil in Tibet. It was cultured in 100 mL erlenmeyer flasks containing 10 mL of synthetic medium consisting of Soyapower 3%,Bran 3%,Starch 0.25%,pH8.8 in this study. The cultures were incubated at 45℃ for 48 h with 160 r/min agitation and the yield of 21.2×104U/mL was obtained. The strain B.L Z-8 can grow at a pH range of 5.0 to 11.0. Its optimum pH is 7.0～8.0. The characteristics of the thermostable α-amylase were also discussed. The optimum temperature and pH for the enzyme were determined as 90℃ and 6.0 respectively. The enzyme lost only 5.4% of its activity when treated at 95℃ for 60 min. It is seen that the thermostability of this enzyme did not rely on Ca 2+.