Tawthep Sarinya, Fukiya Satoru, Lee Ja-Young, Hagio Masahito, Ogura Yoshitoshi, Hayashi Tetsuya, Yokota Atsushi
Laboratory of Microbial Physiology, Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan.
Faculty of Life Sciences, Toyo University, Itakura, Gunma 374-0193, Japan.
J Biosci Bioeng. 2017 Nov;124(5):514-522. doi: 10.1016/j.jbiosc.2017.06.002. Epub 2017 Jul 24.
Understanding the dynamics of secondary bile acid (SBA) formation in the gut by SBA-producing bacteria is important for host health, as SBAs have been shown to affect host pathophysiology and gut microbiota composition. However, our knowledge of SBA producers is limited in light of the diversity of gut microbes. Here, we isolated six novel SBA-producing bacteria from rat cecal contents, all of which were members of known species of gut microbes. Anaerostipes caccae D10, Bacteroides nordii C5, Clostridioides difficile D7, and Clostridium cadaveris G11 were capable of oxidizing cholic acid and chenodeoxycholic acid into 7-oxo-derivatives with varying yields. B. nordii C5 and its type strain JCM 12987 had the highest molar yield, ∼90%. Clostridium disporicum F4 and Clostridium subterminale C4 epimerized cholic acid into ursocholic acid with yields of ∼85%; the corresponding type strains lacked epimerization activity. Furthermore, although not novel as an SBA producer, Clostridium scindens G10 that produced deoxycholic acid from cholic acid was isolated for the first time from rodents. These findings will contribute to elucidation of SBA formation in the gut.
了解产次级胆汁酸（SBA）的细菌在肠道中形成SBA的动态过程对宿主健康很重要，因为已证明SBA会影响宿主病理生理学和肠道微生物群组成。然而，鉴于肠道微生物的多样性，我们对SBA产生菌的了解有限。在这里，我们从大鼠盲肠内容物中分离出六种新型产SBA细菌，它们都是已知肠道微生物物种的成员。粪厌氧棒状菌D10、诺氏拟杆菌C5、艰难梭菌D7和尸毒梭菌G11能够将胆酸和鹅去氧胆酸氧化成产率各异的7-氧代衍生物。诺氏拟杆菌C5及其模式菌株JCM 12987的摩尔产率最高，约为90%。双孢子梭菌F4和近末端梭菌C4将胆酸差向异构化为熊去氧胆酸，产率约为85%；相应的模式菌株缺乏差向异构化活性。此外，虽然作为SBA产生菌并不新颖，但首次从啮齿动物中分离出了从胆酸产生脱氧胆酸的梭状芽孢杆菌G10。这些发现将有助于阐明肠道中SBA的形成。
