Kuo Lun-Cheng, Cheng Wei-Yi, Wu Ren-Yu, Huang Ching-Jang, Lee Kung-Ta
Institute of Microbiology and Biochemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, Taiwan, Republic of China.
Appl Microbiol Biotechnol. 2006 Nov;73(2):314-20. doi: 10.1007/s00253-006-0474-7. Epub 2006 May 20.
Hydrolysis of isoflavone glycosides by Bacillus subtilis natto NTU-18 in black soymilk is reported. At the concentration of 3-5% (w/v), black soymilk in flask cultures, the isoflavones, daidzin, and genistin were highly deglycosylated within 24 h. Deglycosylation of isoflavones was further carried out in a 7-l fermenter with 5% black soymilk. During the fermentation, viable cells increased from 10(3) to 10(9) CFU ml(-1) in 15 h, and the activity of beta-glucosidase appeared at 8 h after inoculation and reached a maximum (3.3 U/ml) at 12 h, then decreased rapidly. Deglycosylation of isoflavone glycosides was observed at the same period, the deglycosylation rate of daidzin and genistin at 24 h was 100 and 75%, respectively. It is significantly higher than the previous reports of fermentation with lactic acid bacteria. In accordance with the deglycosylation of isoflavone glycosides, the estrogenic activity of the 24 h fermented black soymilk for ERbeta estrogen receptor increased to threefold; meanwhile, the fermented broth activated ERalpha estrogen receptor to a less extent than ERbeta. These results suggest that this fermentation effectively hydrolyzed the glycosides from isoflavone in black soymilk and the fermented black soymilk has the potential to be applied to selective estrogen receptor modulator products.
据报道，纳豆芽孢杆菌NTU-18可水解黑豆奶中的异黄酮糖苷。在摇瓶培养中，当黑豆奶浓度为3-5%（w/v）时，黄豆苷和染料木苷等异黄酮在24小时内被高度去糖基化。异黄酮的去糖基化反应在装有5%黑豆奶的7升发酵罐中进一步进行。发酵过程中，活菌数在15小时内从10³CFU/ml增加到10⁹CFU/ml，β-葡萄糖苷酶活性在接种后8小时出现，并在12小时达到最大值（3.3 U/ml），随后迅速下降。同期观察到异黄酮糖苷的去糖基化现象，24小时时黄豆苷和染料木苷的去糖基化率分别为100%和75%。这显著高于之前关于乳酸菌发酵的报道。随着异黄酮糖苷的去糖基化，发酵24小时的黑豆奶对雌激素受体β的雌激素活性增加到三倍；同时，发酵液对雌激素受体α的激活程度低于雌激素受体β。这些结果表明，这种发酵有效地水解了黑豆奶中异黄酮的糖苷，发酵后的黑豆奶有潜力应用于选择性雌激素受体调节剂产品。
