Conversion of cholic acid and chenodeoxycholic acid into their 7-oxo derivatives by Bacteroides intestinalis AM-1 isolated from human feces.
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 7alpha-hydroxysteroid dehydrogenase (7alpha-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 7alpha-HSDH activity. The level of 7alpha-HSDH activity was higher in B. intestinalis AM-1 than in the other two strains under the conditions tested. The 7alpha-HSDH activity in each of the three strains is not induced by CA; instead, it is regulated in a growth phase-dependent manner.
Fukiya
Satoru
S
Laboratory of Microbial Physiology, Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan.
Arata
Miki
M
Kawashima
Hiroko
H
Yoshida
Daisuke
D
Kaneko
Maki
M
Minamida
Kimiko
K
Watanabe
Jun
J
Ogura
Yoshio
Y
Uchida
Kiyohisa
K
Itoh
Kikuji
K
Wada
Masaru
M
Ito
Susumu
S
Yokota
Atsushi
A
D000328:Adult; D015373:Bacterial Typing Techniques; D001439:Bacteroides / Q000145:classification / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D001441:Bacteroides fragilis / Q000378:metabolism; D001711:Biotransformation; D002635:Chenodeoxycholic Acid / Q000378:metabolism*; D019826:Cholic Acid / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D003840:Deoxycholic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D005243:Feces / Q000382:microbiology*; D005260:Female; D006801:Humans; D008095:Lithocholic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D008297:Male; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D055815:Young Adult
D003470:Culture Media; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S; D003840:Deoxycholic Acid; D002635:Chenodeoxycholic Acid; C023867:7-ketodeoxycholic acid; C023020:7-ketolithocholic acid; D008095:Lithocholic Acid; D019826:Cholic Acid