Department of Food and Nutrition, Obesity/Diabetes Center, Hoseo University, 165 Sechul-Ri, BaeBang-Yup, Asan-Si, Chungnam-Do, 336-795, South Korea.
Food Functional Research Division, Korean Food Research Institutes, Sungnam, South Korea.
Arch Microbiol. 2019 Oct;201(8):1009-1017. doi: 10.1007/s00203-019-01665-5. Epub 2019 May 8.
Equol improves menopausal symptoms and it is synthesized from daidzein, one of the isoflavonoids in soybeans, by the bacteria in the large intestines of some people. The purpose of this study was to isolate equol-producing bacteria using daidzein from the intestinal microflora and to produce equol-containing chungkookjang (short-term fermented soybean). Equol-producing bacteria from the feces of Sprague-Dawley female rats were isolated using media containing daidzein. The isolated bacteria were cultured in thioglycollate media and equol production was identified through thin-layer chromatography and ultraperformance liquid chromatography-mass spectrometry. The bacteria were identified by 16S rRNA sequencing. The rate of equol production in different concentrations of daidzein was assessed. The expression of genes that code for enzymes associated with the production of equol from daidzein was detected through reverse transcription quantitative PCR. The bacterium we isolated was Lactobacillus intestinalis (LC096206.1, 99%). L. intestinalis was found to express daidzein reductase, dihydrodaidzein reductase, and tetrahydrodaidzein reductase, the enzymes involved in producing equol from daidzein. The conversion rate of equol from daidzein was highest (29.5%) using 200 μM daidzein for 48 h of incubation. When chungkookjang fermented with Bacillus amyloquencies SRCM100001 was incubated with L. intestinalis, 0.32 ± 0.04 mg equol/g chungkookjang was produced. In conclusion, L. intestinalis efficiently produces equol from not only daidzein but also in chungkookjang.
大豆异黄酮中的大豆苷元可被大肠内的某些细菌转化为雌马酚，雌马酚可以改善更年期症状。本研究旨在从肠道微生物群中分离出利用大豆苷元产生雌马酚的细菌，并生产含有雌马酚的葱豆酱（短期发酵大豆）。使用含大豆苷元的培养基从 Sprague-Dawley 雌性大鼠粪便中分离产雌马酚细菌。将分离出的细菌在巯基醋酸盐培养基中培养，并通过薄层层析和超高效液相色谱-质谱联用技术鉴定雌马酚的产生。通过 16S rRNA 测序鉴定细菌。评估不同大豆苷元浓度下雌马酚的产生率。通过反转录定量 PCR 检测编码与大豆苷元生成雌马酚相关酶的基因表达。我们分离出的细菌为肠道乳杆菌（LC096206.1，99%）。发现肠道乳杆菌表达大豆苷元还原酶、二氢大豆苷元还原酶和四氢大豆苷元还原酶，这些酶参与大豆苷元生成雌马酚。在 200 μM 大豆苷元孵育 48 小时时，雌马酚的转化率最高（29.5%）。当用 Bacillus amyloquencies SRCM100001 发酵葱豆酱并与肠道乳杆菌共孵育时，可产生 0.32±0.04mg/g 葱豆酱的雌马酚。总之，肠道乳杆菌不仅能从大豆苷元中高效产生雌马酚，还能在葱豆酱中产生雌马酚。
