Tauroconjugation of cholic acid stimulates 7 alpha-dehydroxylation by fecal bacteria
Tauroconjugation of cholic acid stimulates 7 alpha-dehydroxylation by fecal bacteria
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DOI：
10.1128/aem.62.2.656-661.1996
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发表时间：
1996-02-01
影响因子：
4.4
通讯作者：
Eyssen, H
中科院分区：
文献类型：
--
作者：
VanEldere, J;Celis, P;Eyssen, H
我们检查了胆酸结合类型（牛磺酸结合、甘氨酸结合或非结合胆酸）对肠道植物群对胆酸7 α-脱羟基的影响。研究了粪便培养物、由从肠道分离的7种细菌物种的混合物组成的限定有限植物群的培养物以及7 α-脱羟基梭菌属物种加胆酸解结合拟杆菌属物种的二元培养物中的胆酸7 α-脱羟基。我们发现，胆酸的牛磺结合显著（P < 0.05）增加了粪便培养物中胆酸的细菌7 α-脱羟基转化为脱氧胆酸的比例，从34%增加到55%，在限定的有限粪便培养物中从45%增加到60%，在二元培养物中从75%增加到100%。等摩尔浓度的游离牛磺酸在粪便培养物或限定的有限植物群中不刺激7 α-脱羟基，但游离牛磺酸在二元培养物中刺激7 α-脱羟基。在梭菌属菌株9/1加上拟杆菌属菌株R1的二元培养物中，能够增加牛磺胆酸的7 α-去羟基化的最小植物群，菌株R1解结合牛磺酸并将其快速还原为H2S。除非存在牛磺酸或另一种适当的可还原硫源，否则拟杆菌属菌株R1不生长。梭菌属菌株9/1不生长或7 α-脱羟基化，除非存在H2S或另一种还原硫源。我们得出结论，增加7 α-脱羟基牛磺酸共轭胆酸依赖于还原牛磺酸H2S，这是一个必要的生长因子为7 α-脱羟基细菌。
We examined the effect of the type of cholic acid conjugation (taurine-conjugated, glycine-conjugated, or unconjugated cholic acid) on cholic acid 7 alpha-dehydroxylation by intestinal flora. Cholic acid 7 alpha-dehydroxylation in fecal cultures, in cultures of a defined limited flora consisting of a mixture of seven bacterial species isolated from the intestinal tract, and in a binary culture of a 7 alpha-dehydroxylating Clostridium species plus a cholic acid-deconjugating Bacteroides species was studied. We found that tauroconjugation of cholic acid significantly (P < 0.05) increased bacterial 7 alpha-dehydroxylation of cholic acid into deoxycholic acid from 34 to 55% in fecal cultures, from 45 to 60% in defined limited fecal cultures, and from 75 to 100% in binary cultures. Equimolar concentrations of free taurine did not stimulate 7 alpha-dehydroxylation in fecal cultures or in the defined limited flora, but free taurine did stimulate 7 alpha-dehydroxylation in the binary culture. In the binary culture of Clostridium species strain 9/1 plus Bacteroides species strain R1, the minimal flora capable of increased 7 alpha-dehdroxylation of taurocholic acid, strain R1 deconjugated taurine and rapidly reduced it to H2S. Bacteroides species strain R1 did not grow unless taurine or another appropriate reducible sulfur source was present. Clostridium species strain 9/1 did not grow or 7 alpha-dehydroxylate unless H2S or another source of reduced sulfur was present. We conclude that the increased 7 alpha-dehydroxylation of tauroconjugated cholic acid depends on the reduction of taurine to H2S, which is a necessary growth factor for the 7 alpha-dehydroxylating bacteria.