一株产纳豆激酶菌株的分离筛选及鉴定

对能产生纳豆激酶的菌群进行了筛选,分离得到了1株具有较高纤溶活性的菌株N391,其纳豆激酶相当于1722.4U/mL尿激酶的酶活。利用细菌16S rDNA通用引物对其16S rRNA进行PCR扩增,得到1511bp的片段,该PCR产物序列通过Blast软件在NCBI网站中进行同源性比较,通过DNA MAN和MAGE3.1软件绘制系统发育树,结果表明,菌株N391的16S rRNA序列(DQ906100)与枯草芽胞杆菌(Bacillus subtilis)的16S rRNA序列的同源性在99%以上,在系统发育树中,菌株N391与Bacillus subtilis在同一分支,且遗传距离最短。结合常规的形态、生理生化鉴定,N391的形态及大部分生理生化特征与Bacillus subtilis极为相似,表明菌株N391属于Bacillus subtilis的1个菌株,由此初步确定该菌在微生物系统发育学上的地位。

Screening and Identification of a Strain Producing Nattokinase

In order to develop natto health products with specific physiological activity,one fibrinolytic spore—forming strain named N391 was isolated by screening the microflora producing nattokinase,whose nattokinase production equals to 1722.4U/mL of urokinase activity.A 1511bp fragment of 16S ribosomal RNA was obtained from total DNA of strain N391 by PCR amplification,using the universal primer of bacte- rial 16S ribosome DNA,Sequence analysis was carried out by Blast on NCBI website and the phylogenetic tree was constructed by DNA MAN and MEGA3.1 software.The results show that N391(DQ906100)shared 99. 60% 16S ribosomal RNA sequence homology with Bacillus subtilis.Strain N391 and Bacillus subtilis were in the same branch of the phylogenetic tree and their genetic distance was the shortest.Combining the similarity of morphological and physiological characters,strain N391 was identified as Bacillus subtilis,and the position of the strain in microbiological phylogeny was set up.