Conversion of cholic acid and chenodeoxycholic acid into their 7-oxo derivatives by Bacteroides intestinalis AM-1 isolated from human feces
Conversion of cholic acid and chenodeoxycholic acid into their 7-oxo derivatives by Bacteroides intestinalis AM-1 isolated from human feces
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DOI：
10.1111/j.1574-6968.2009.01531.x
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发表时间：
2009-04-01
影响因子：
2.1
通讯作者：
Yokota, Atsushi
中科院分区：
文献类型：
--
作者：
Fukiya, Satoru;Arata, Miki;Yokota, Atsushi
从人类粪便中分离出次级胆汁酸细菌，以提高我们对肠道微生物群功能多样性和冗余性的认识。使用营养贫乏的琼脂培养基总共分离出 619 个细菌菌落，并通过液体培养物和薄层色谱法检查每个菌落的次级胆汁酸形成水平。通过 16S rRNA 基因测序和生化检测分析了 5 株菌株，其中一种被鉴定为肠拟杆菌 AM-1，此前并未将其视为次级胆汁酸生产者。 GC-MS 显示，肠杆菌 AM-1 将胆酸 (CA) 和鹅去氧胆酸分别转化为其 7-氧代衍生物，7-氧代-脱氧胆酸 (7-oxo-DCA) 和 7-氧代-石胆酸。因此，肠双歧杆菌AM-1具有7α-羟基类固醇脱氢酶(7α-HSDH)活性。在液体培养中，与已知具有7α-HSDH活性的大肠杆菌HB101和脆弱拟杆菌JCM11019(T)相比，肠杆菌AM-1表现出相对较高的7-oxo-DCA生产率。在测试条件下，肠双歧杆菌 AM-1 中的 7 α-HSDH 活性水平高于其他两种菌株。三种菌株中的 7 α-HSDH 活性均不是由 CA 诱导的；相反，它以生长阶段依赖的方式进行调节。
Secondary bile acid-producing bacteria were isolated from human feces to improve our appreciation of the functional diversity and redundancy of the intestinal microbiota. In total, 619 bacterial colonies were isolated using a nutrient-poor agar medium and the level of secondary bile acid formation was examined in each by a liquid culture, followed by thin-layer chromatography. Of five strains analyzed by 16S rRNA gene sequencing and biochemical testing, one was identified as Bacteroides intestinalis AM-1, which was not previously recognized as a secondary bile-acid producer. GC-MS revealed that B. intestinalis AM-1 converts cholic acid (CA) and chenodeoxycholic acid into their 7-oxo derivatives, 7-oxo-deoxycholic acid (7-oxo-DCA) and 7-oxo-lithocholic acid, respectively. Thus, B. intestinalis AM-1 possesses 7 alpha-hydroxysteroid dehydrogenase (7 alpha-HSDH) activity. In liquid culture, B. intestinalis AM-1 showed a relatively higher productivity of 7-oxo-DCA than Escherichia coli HB101 and Bacteroides fragilis JCM11019(T), which are known to possess 7 alpha-HSDH activity. The level of 7 alpha-HSDH activity was higher in B. intestinalis AM-1 than in the other two strains under the conditions tested. The 7 alpha-HSDH activity in each of the three strains is not induced by CA; instead, it is regulated in a growth phase-dependent manner.