College of Food Science, South China Agricultural University, Guangzhou, China.
Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Science, South China Agricultural University, Guangzhou, China.
FEMS Microbiol Lett. 2021 May 11;368(8). doi: 10.1093/femsle/fnab046.
Equol, which produced from daidzein (one of the principal isoflavones), is recognized to be the most resultful in stimulating an estrogenic and antioxidant response. The daidzein transformation was studied during fermentation of five growth media inoculated with feces from a healthy human, and a daidzein conversion strain was isolated. To enrich the bacterial population involved in daidzein metabolism in a complex mixture, fecal samples were treated with antibiotics. The improved propidium monoazide combined with the quantitative polymerase chain reaction (PMAxx-qPCR) assay showed that the ampicillin treatment of samples did result in a reduction of the total visible bacteria counts by 52.2% compared to the treatment without antibiotics. On this basis, the newly isolated rod-shaped, Gram-positive anaerobic bacterium, named strain Y11 (MN560033), was able to metabolize daidzein to equol under anaerobic conditions, with a conversion ratio (equol ratio: the amount of equol produced/amount of supplemented daizein) of 0.56 over 120 h. The 16S rRNA partial sequence of the strain Y11 exhibited 99.8% identity to that of Slackia equolifaciens strain DZE (NR116295). This study will provide new insights into the biotransformation of equol from daidzein by intestinal microbiota from the strain-level and explore the possibility of probiotic interventions.
雌马酚是大豆异黄酮之一，其代谢产物，被认为是最有效的雌激素和抗氧化剂反应刺激物。本研究通过在五种接种有健康人体粪便的生长培养基中发酵大豆苷元，来研究其在发酵过程中的转化，同时分离出大豆苷元转化菌株。为了在复杂混合物中富集参与大豆苷元代谢的细菌种群，对粪便样本进行了抗生素处理。改良的吖啶橙单重荧光定量聚合酶链反应（PMAxx-qPCR）检测表明，与未用抗生素处理的样本相比，氨苄青霉素处理的样本中总可见细菌计数减少了 52.2%。在此基础上，从粪便中分离出一种新的杆状、革兰氏阳性、厌氧细菌，命名为 Y11 株（MN560033），该菌株能够在厌氧条件下将大豆苷元代谢为雌马酚，在 120 小时内的转化率（雌马酚比：产生的雌马酚量/添加的大豆苷元量）为 0.56。菌株 Y11 的 16S rRNA 部分序列与 Slackia equolifaciens 菌株 DZE（NR116295）的序列具有 99.8%的同一性。本研究将从菌株水平深入了解肠道微生物群对大豆苷元转化为雌马酚的生物转化，并探索益生菌干预的可能性。
