Minamida Kimiko, Tanaka Michiko, Abe Ayumi, Sone Teruo, Tomita Fusao, Hara Hiroshi, Asano Kozo
Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita 9, Nishi 9, Sapporo, Hokkaido, Japan.
J Biosci Bioeng. 2006 Sep;102(3):247-50. doi: 10.1263/jbb.102.247.
Isoflavones (mainly daidzein and genistin) belong to the flavonoid group of compounds and are classified as phytoestrogens. In the intestine, daidzin is converted to daidzein by beta-glucosidase, and then daidzein is converted to O-desmethylangolensin (O-DMA) or equol via dihydrodaidzein by enzymes of intestinal bacteria. We isolated, for the first time, an anaerobic gram-positive rod-shaped strain capable of producing equol from daidzein. Its 16S rDNA gene sequence (1428 bp) showed 99% similarity with that of the human intestinal bacterium SNU-Julong 732 (AY310748) and 93% similarity with that of Eggerthella lenta ATCC 25559(T) (AF292375). This strain converted daidzein to equol via dihydrodaidzein in an equol-assay medium anaerobically. The addition of butyric acid and arginine increased the conversion ratio of daidzein to equol 4.7- and 4.5-fold, respectively.
异黄酮（主要是大豆苷元和染料木苷）属于黄酮类化合物，被归类为植物雌激素。在肠道中，大豆苷被β-葡萄糖苷酶转化为大豆苷元，然后大豆苷元通过肠道细菌的酶经二氢大豆苷元转化为O-去甲基安哥拉紫檀素（O-DMA）或雌马酚。我们首次分离出一种能够从大豆苷元产生雌马酚的厌氧革兰氏阳性杆状菌株。其16S rDNA基因序列（1428 bp）与人类肠道细菌SNU-Julong 732（AY310748）的序列相似度为99%，与迟缓埃格特菌ATCC 25559(T)（AF292375）的序列相似度为93%。该菌株在雌马酚检测培养基中厌氧条件下通过二氢大豆苷元将大豆苷元转化为雌马酚。添加丁酸和精氨酸分别使大豆苷元向雌马酚的转化率提高了4.7倍和4.5倍。
