一株碱性淀粉酶产生菌的分离及酶学特性分析

目的]筛选出能用于生物印染的碱性淀粉酶产生菌。方法]利用Horikoshi培养基从农田土壤中分离碱性淀粉酶产生菌,并采用DNS法和碘量法测定粗酶液中淀粉酶的酶学性质。结果]共分离到9株碱性淀粉酶产生菌,对其中水解圈最大的菌株703进行16S rDNA序列同源性比对,结果显示其与嗜碱性芽孢杆菌Bacillus pseudofirmus OF4的16S rDNA序列一致性达100%。对该菌发酵粗酶的酶学性质研究表明该碱性淀粉酶的最适温度为50℃,最适pH为9.5,50℃下处理30 min后酶活残存74.7%。结论]该研究筛选出了能用于生物印染的碱性淀粉酶产生菌,所产淀粉酶热稳定性较好,且具有强的碱耐受性,表明该酶具有应用于生物印染的潜在利用价值。

Isolation of Alkaline Amylase Producing Bacteria and Analysis of the Enzymatic Characteristics

Objective] To isolate a strain capable of producing alkaline amylase that can apply in textile printing and dyeing.Method] Alkaline amylase producer was isolated from agricultural soil by Horikoshi culture medium,and the enzymatic characteristics were analyzed by iodometry method and DNS method.Result] Nine strains with alkaline amylase activity were obtained,the one with the best enzymatic activity was designated as 703,703 was identified by its morphological characteristics and 16S rDNA sequence homology,the 16S rDNA sequence of the isolate 703 shows high identity(100%) with facultative alkaliphilic Bacillus pseudofirmus OF4.The maximal activity of amylase from fermentation supernatant was observed at 50 ℃ and pH 9.5.More than 74.4% of the residual activity was remained after preincubating at 50 ℃ for 30 minutes.Conclusion] The amylase has a good thermostability,and exhibits a strong alkali tolerance,the enzyme activity was high over a wide pH range,especially in the pH value(9.5-10.5).The enzymatic characteristics indicate its potential application value in textile printing and dyeing.