一株产低温碱性淀粉酶蕈状芽孢杆菌的分离筛选和发酵优化

Isolation and screening of psychrophilic and alkaline amylase-producing Bacillus mycoides strain 3F1 and the optimum fermentation for enzyme production

摘要:

本研究的目的是从生态环境独特而复杂的西藏林芝地区的土壤样品中挖掘所蕴藏的特殊淀粉酶微生物资源.采用淀粉酶功能筛选的方法获得一株低温碱性淀粉酶生产菌株,编号为3F1.其酶活最适条件为10 ℃、pH 10.2.通过16S rDNA序列分析法鉴定该菌株为蕈状芽孢杆菌(Bacillus mycoides),并将其命名为Bm3F1.通过发酵条件的逐步优化,最终确定其最佳发酵条件为:发酵培养基中添加1.5%可溶性淀粉,培养基初始pH 7.2,装液量10 mL/250 mL,菌体接种量9.0%,发酵温度30 ℃,发酵时间18 h,经优化后可将菌株的酶活提升至13.58 U/mL. 表明从西藏林芝地区分离的Bm3F1具有在低温和碱性条件下产较高酶活淀粉酶的特性.

Abstract:

This study is intended to explore the microbial resource contained in the soil samples of Nyingchi, Tibet, which has a unique and complex ecological environment. A psychrophilic and alkaline amylase-producing strain was obtained by the amylase functional screening method, numbered 3F1. The optimum conditions of amylase activity were 10 ℃ and pH 10.2. According to the 16S rDNA sequencing and phylogenetic analysis result, this strain was classified as Bacillus mycoides and named Bm3F1. Through the gradual optimization of fermentation conditions, the optimum fermentation condition for Bm3F1 was determined as follows: fermentation medium was supplemented with 1.5% soluble starch, the initial pH was 7.2, the liquid volume was 10 mL/250 mL, the bacterial inoculum was 9.0%, and the fermentation temperature and time were 30 ℃ and 18 hours, respectively. Under the optimum conditions, the amylase activity from Bm3F1 could be increased to 13.58 U/mL. The results showed that Bm3F1 isolated from Nyingchi, Tibet, has the characteristics of producing high activity amylase under low temperature and alkaline conditions.