一株转化大豆苷元为S-雌马酚菌株的筛选和鉴定

【目的】筛选一株可转化大豆苷元为S-雌马酚的微生物菌株,并对该菌株进行鉴定。【方法】在厌氧条件下采用抗生素抑制非目标菌生长并结合稀释涂平板法进行菌株分离,分离可转化大豆苷元生成S-雌马酚的肠道细菌,并对产物进行结构鉴定。之后通过16S rDNA序列分析,构建该菌系统进化树,结合菌体形态及菌落特征,确立该菌系统发育学地位。【结果】从大鼠肠道内筛选分离到一株可以将大豆苷元转化为S-雌马酚的革兰氏阴性兼性厌氧菌株LH-52(JN861767),16S rDNA序列测序结果 BLAST比对表明该菌株与奇异变形杆菌(Proteus mirabilis)相似度达到了99%,结合形态特征和生理生化实验结果鉴定该菌为奇异变形杆菌。根据HPLC保留时间、质谱、核磁共振等波谱数据分析确定产物为S-雌马酚。【结论】菌株P.mirabilis LH-52为首次筛选到的可转化大豆苷元为S-雌马酚的兼性厌氧菌,相对于文献报道的严格厌氧菌更适合于工业化生产。

Screening and identification of a bacterium capable of converting daidzein to S-equol

Objective] To screen and identify a bacterium capable of converting daidzein to S-equol.Methods] We used antibiotics to limit unrelated bacterial growth and enrich the target bacteria,and isolated the aim bacterial strain from rat intestine.The metabolite of daidzein was tested by HPLC,MS and NMR.The taxonomic group of the strain was identified by 16S rDNA sequence analysis and phylogenetic tree;the strain’s morphological and physiological biochemical characters were also tested.Results] A gram-negative facultative bacterial strain LH-52(JN861767) capable of transforming daidzein to S-equol was isolated.Basic Local Alignment Search Tool(BLAST) search of LH-52’s 16S rDNA sequence on GenBank suggested that this strain has 99% similarity to that of Proteus mirabilis,the morphological and physiological biochemical characteristics of LH-52 also showed highly similarity to P.mirabilis.Based on these data,we identified LH-52 as P.mirabilis,and named it as P.mirabilis LH-52.The results of HPLC,MS and NMR suggested that the metabolite of daidzien was S-equol.Conclusions] Bacteria strain P.mirabilis LH-52 was the first reported facultative bacteria strain capable of converting daidzein to S-equol,and might be more suitable in industrial application than obligate anareobic bacterial strains.