1株素食者产雌马酚肠道菌的分离与鉴定

Isolation and Identification of An Equol-Producing Bacterial Strain from Vegetarian Intestinal Tract

以素食者粪便为样品,大豆异黄酮为底物,对产雌马酚的肠道菌进行分离培养及鉴定。采用紫外光谱法对雌马酚定性、定量测定,用肉眼观察、扫描电镜、生理生化、16S rDNA全序测序方法对分离得到的LJ-G1肠道菌进行菌株鉴定。结果表明:麦康凯和BHI培养基、厌氧平板划线培养法更适于产雌马酚肠道菌的分离筛选。采取10 g粪样稀释到10-5接种,在pH 7.3、温度37℃、厌氧培养36 h的条件下,培养基中雌马酚产出量达到10μg/mL以上。经鉴定分离得到的LJ-G1菌株为G-杆菌;根据生理生化反应结果,查阅《常见细菌系统鉴定手册》,确定LJ-G1为河生肠杆菌;16S rDNA全序测序显示与肠杆菌同源性达99%。

An intestinal bacterial strain with the ability to metabolize soy isof lavone to equol was isolated from vegetarian feces. Qualitative and quantitative analysis of equol was performed by ultraviolet spectrophotometry. The isolated strain was identifi ed through naked-eye observation, scanning electron microscope, physiological and biochemical characterization and 16S rDNA full-length sequencing. The results showed that Makanke medium, BHI medium and anaerobic plate streaking cultivation method were suitable for isolating intestinal bacteria producing equol. The optimal culture conditions for enhanced equol production were 10 g of fecal sample diluted in advance to 10-5 inoculated into 6 mg of substrate at an initial medium pH of 7.3, followed by anaerobic culture at pH 7.3 for 36 h. The strain was identifi ed as LJ-G1, a Gam-negative bacillus. According to physiological and biochemical properties and referring the Common Bacterial System Identif ication Manual, LJ-G1 belonged to Enterobacter amnigenus. The results of 16S rDNA full-length sequencing showed 99% homology with the intestinal bacterium.