一株产α-高温淀粉酶的地衣芽孢杆菌的分离和筛选

Isolation and screening of Bacillus licheninformis LT containing thermostable α-amylase

从西藏当雄温泉附近的土壤中用锥虫蓝平板,55℃培养,筛选到一株分泌高温淀粉酶的菌株,经生理生化初步鉴定后,克隆16s rDNA基因测序,提交GenBank比对后,鉴定为地衣芽孢杆菌（Bacillus licheninformis）,命名为B.licheninformis LT。通过对B.licheninformis LT的生长条件和产酶条件的研究表明：该菌高温特性良好,最高可以在65℃生长,产酶最适温度50℃;可以在pH3.0~pH11.0的LB培养基中生长,最佳产酶pH10.0,LB培养基加入淀粉诱导,发酵液酶活可达80U。对该菌所产α-高温淀粉酶的性质研究表明：酶的最适反应温度为95℃,100℃处理60min发酵液酶活力没有明显下降,最适酶作用pH10.0,添加1g/L的钙离子具有激活作用。

A bactcrial stain with high activity of thermostable α-amylase was screened from hot spring of Dangxiong, Tibet. It was identified as Bacillus licheninformis by tests of biochemistry, physiology and 16s rDNA sequencing. It was named as B. licheninformi LT. The cell growth and enzyme production conditions of the B. licheninformis were tested, and found that the strain produced 80U/mL raw amylase activity in broth. The maximal temperature for growth was 65 ℃ and the optimum temperaturc was 50 ℃ ; the optimal pH for growth was 3.0- 11.0 and pH 10.0 for enzyme production respectively. The characteristics of the thcrmostable α-amylase were also discussed. The optimal temperature and pH for the enzyme were determined as 95 ℃ and 10.0 respectively. The enzyme kept most of its activity when treated at 100 ℃ for 60 min. It was found that 1 g/L Ca^2＋ could enhance the activity of α-amylasc from B. lictwninforrni LT.