一株高产淀粉酶嗜盐海洋菌的筛选鉴定及其发酵条件研究

Screening and identification of a high amylase-producing halophilic marine bacterium and optimization of fermentation conditions

采用透明圈法从本实验室保存的40株海洋菌中,筛选得到15株具有淀粉酶活性的菌株,其中编号为399S3-1 1519的菌株具有较高的淀粉酶生产能力。通过16S rDNA分子鉴定,并结合菌落形态与KOH鉴定,确定其属于芽孢杆菌属。随后,对该菌株的发酵条件进行研究,确定其最佳碳源为淀粉,最佳氮源为大豆粉,最适温度37℃,最适pH值为7.0,最佳盐浓度5%,最佳底物浓度2%,最佳装液量50mL(250mL摇瓶),最佳接种量为3%;正交优化试验证明碳源和盐度对该菌产酶有较大影响,在最佳产酶条件下,酶活可达到293.8U/mL,比优化前提高了0.8倍。

15 amylase-producing strains were screened from 40 marine bacteria according the size of the transparent circle, in which 399S3-1 1519 had the highest amylase activity. Through analysis of 16SrDNA gene, characterization of colony morphology and identification with KOH, 399S3-1 1519 was identified as Bacillus algicola and used for further optimization of fermentation conditions. Optimum sources of carbon and nitrogen were starch and soybean powder, respectively. The optimal conditions were as followed： Saline salinity 5%, substrate concentration 2%, liquid volume 50ml in 250ml shaking flask and inoculum 3%, temperature 37qE and initial pH value 7.0. The results of orthogonal test showed that carbon and saline salini- ty had a great impact on amylase production. Under the optimum conditions, enzyme activity could reach 293.8U/ml, which was 0.8 fold higher than that before optimization.