一株来自蚯蚓的产纤溶酶蜡状芽孢杆菌Bacillus cereus的筛选及鉴定

Screening and identification of a Bacillus cereus strain producing fibrinolytic enzyme from earthworm

对来自4个不同省份的5条蚯蚓的肠道及体表细菌进行分离,共获得122株细菌。通过脱脂奶粉平板法初筛,纤维蛋白平板法复筛,以透明圈为筛选标记,共筛选出产纤溶酶菌株12株,其中菌株SC-3-W-3的纤溶酶活力较高,达到了538.64 U/mL(相当于尿激酶的活力单位)。通过对其形态、培养、生理生化特征进行研究,发现其与蜡状芽孢杆菌Bacillus cereus Frankland的特征很相符。进一步对SC-3-W-3的16S rDNA序列及系统发育分析表明,该菌株与蜡状芽孢杆菌的同源性高达100%。综合生理生化及16S rDNA序列比对结果,将SC-3-W-3菌株鉴定为蜡状芽孢杆菌。

One hundred and twenty-two bacteria strains were isolated from the intestinal tracts and body surface of five earthworms collected from four different provinces.Twelve fibrinolytic enzyme pro-ducing strains were screened based on the size of halo zone by using powdered skim milk and fibrous protein as the first and second round screening substrates,respectively.SC-3-W-3 strain with high fi-brinolytic enzyme activity was identified as Bacillus cereus based on physiological and biochemical characteristics,as well as 16S rDNA.The fibrinolytic enzyme activity of SC-3-W-3 strain was up to 538.64 U/mL.