中温大曲产淀粉酶菌株的筛选鉴定及培养条件优化

为获得高产淀粉酶菌株，丰富淀粉酶生产菌株资源，该研究以中温大曲为样品，利用淀粉水解圈法初筛、摇瓶发酵复筛得到高产淀粉酶菌株，结合菌落形态观察、革兰氏染色和16S r RNA同源序列分析对其进行菌种鉴定，通过单因素试验、Plackett-Burman试验、最陡爬坡试验和Box-Behnken试验确定其产淀粉酶的最佳培养条件。结果表明，共分离筛选得到6株产淀粉酶菌株，其中一株产淀粉酶活最高的菌株（编号为DQ47）被鉴定为枯草芽孢杆菌（Bacillus subtilis），其最佳培养条件为：可溶性淀粉60 g/L，酵母粉37 g/L，发酵温度39℃，装液量85 m L/250 m L，转速175 r/min，初始p H值6，接种量3%。在此优化条件下，淀粉酶活力为8 158.23 U/m L，是优化前的14.75倍。

Isolation,identification and culture conditions optimization of amylase-producing strains in medium-temperature Daqu

To obtain high amylase-producing strains and enrich the resources of amylase-producing strains, using medium-temperature Daqu as the sample, the high amylase-producing strains were screened by primary screening of starch hydrolysis circle method and re-screening of shaking flask fermentation, and then the strain was identified by colony morphology observation, Gram staining and 16S rRNA homologous sequence analysis. The optimal culture conditions were determined by single-factor tests, Plackett-Burman tests, steepest climb tests and Box-Behnken tests. The results showed that six strains of amylase-producing bacteria were isolated and screened, and one strain with the highest amylase-producing activity (No. DQ47) was identified as Bacillus subtilis. The optimal culture conditions were as follows: soluble starch 60 g/L, yeast powder 37 g/L, fermentation temperature 39 ℃, loading volume 85 ml/250 ml, rotation speed 175 r/min, initial pH 6, inoculum 3%. Under the optimized conditions, the amylase activity was 8 158.23 U/ml, which was 14.75 times that of before optimization.