Isolation of an isoflavone-metabolizing, Clostridium-like bacterium, strain TM-40, from human faeces

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The metabolism of isoflavones by gut bacteria plays a key role in the availability and bioactivation of these compounds in the intestine. Daidzein and genistein are the most common dietary soy isoflavones. While daidzein conversion yielding equol has been known for some time, the corresponding formation of 5-hydroxyequol from genistein has not been reported previously. We isolated a strictly anaerobic bacterium (Mt1B8) from the mouse intestine which converted daidzein via dihydrodaidzein to equol as well as genistein via dihydrogenistein to 5-hydroxy-equol. Strain Mt1B8 was a gram-positive, rod-shaped bacterium identified as a member of the Coriobacteriaceae. Strain Mt1B8 also transformed dihydrodaidzein and dihydrogenistein to equol and 5-hydroxy-equol, respectively. The conversion of daidzein, genistein, dihydrodaidzein, and dihydrogenistein in the stationary growth phase depended on preincubation with the corresponding isoflavonoid, indicating enzyme induction. Moreover, dihydrogenistein was transformed even more rapidly in the stationary phase when strain Mt1B8 was grown on either genistein or daidzein. Growing the cells on daidzein also enabled conversion of genistein. This suggests that the same enzymes are involved in the conversion of the two isoflavones.

“…strain HGH6 and Clostridium-like strain TM-40 from human feces and Lactobacillus sp. strain Niu-O16 from the bovine rumen convert daidzein to dihydrodaidzein (23,45,52). Eggerthella sp.…”

Section: Resultsmentioning

confidence: 99%

“…The microbiotas of animals, including rats and mice, uniformly produce equol from daidzein (1,5,7,27,53). So far, only a few bacterial strains involved in equol formation have been described, and some of these strains catalyze only single reaction steps (23,29,31,45,49,52,54).…”

mentioning

confidence: 99%

Conversion of Daidzein and Genistein by an Anaerobic Bacterium Newly Isolated from the Mouse Intestine

Matthies¹,

Clavel

Gütschow

et al. 2008

120

“…strain Niu-O16 (29); a human intestinal Clostridium sp. strain, HGH6 (8); and a Clostridium-like bacterium strain, TM-40 (27), to name a few-were reported to reduce daidzein into DHD. Wang et al (29) attempted to establish the stereochemistry of daidzein reduction into DHD by strain Niu-O16.…”

Section: Discussionmentioning

confidence: 99%

“…An anaerobic bacterium, Clostridium sp. strain HGH6 (8), and a Clostridium-like strain, TM-40 (27), were found to reduce daidzein into DHD, and the C-ring cleavage was executed by a strain of Eubacterium (25). A human intestinal bacterium that could produce equol was first reported in 2005.…”

mentioning

confidence: 99%

Stereospecific Biotransformation of Dihydrodaidzein into (3 S )-Equol by the Human Intestinal Bacterium Eggerthella Strain Julong 732

Kim

Han

et al. 2009

“…This bacterium is spherical and Gram positive and is a strain of L. garvieae. The application of Lactococcus 20-92 in probiotics is advantageous because L. garvieae is not pathogenic or toxic to humans.To date, other bacterial strains that are capable of transforming daidzein to dihydrodaidzein or equol have been isolated (9,21,22,23,29,32,36,37). Daidzein is thought to be metabolized by human intestinal bacteria to equol or to Odesmethylangolensin via dihydrodaidzein and tetrahydrodaidzein (14,15,22,32); however, neither the enzymes involved in the metabolism of daidzein to equol nor even the metabolic pathway has been clarified fully for equol-producing bacteria.…”

mentioning

confidence: 99%

Cloning and Expression of a Novel NADP(H)-Dependent Daidzein Reductase, an Enzyme Involved in the Metabolism of Daidzein, from Equol-Producing Lactococcus Strain 20-92

Shimada

Yasuda

Takahashi

et al. 2010

Equol is a metabolite produced from daidzein by enteric microflora, and it has attracted a great deal of attention because of its protective or ameliorative ability against several sex hormone-dependent diseases (e.g., menopausal disorder and lower bone density), which is more potent than that of other isoflavonoids. We It was further suggested that L-DZNR was an NAD(H)/NADP(H):flavin oxidoreductase belonging to the old yellow enzyme (OYE) family. Recombinant histidine-tagged L-DZNR was expressed in Escherichia coli.The recombinant protein converted daidzein to (S)-dihydrodaidzein with enantioselectivity. This is the first report of the isolation of an enzyme related to daidzein metabolism and equol production in enteric bacteria.Isoflavones are flavonoids present in various plants and are known to be abundant in soybeans and legumes. These compounds have been called phytoestrogens because their chemical structure is similar to that of the female sex hormone, estrogen. Isoflavones have an ability to bind to estrogen receptors and show protection against or improvement in several sex hormone-dependent diseases, such as breast cancer, prostate cancer, menopausal disorder, lower bone density, and hypertension, due to their weak agonistic or antagonistic effects (1,19,27).Daidzein is one of the main soy isoflavonoids produced from daidzin by the glucosidase of intestinal bacteria (17). Equol is a metabolite produced from daidzein by the enterobacterial microflora (5). Recently, equol has attracted a great deal of attention because its estrogenic activity is more potent than that of other isoflavonoids, including daidzein (27). It is well known that individual variation exists in the ability of these enteric microflora to produce equol and that less than half the human population is capable of producing equol after ingesting soy isoflavones (3). Therefore, to increase the production of equol in the enteric environment of each individual, the development of probiotics using safe bacteria which have the ability to produce equol from daidzein is ongoing.Lactococcus strain 20-92 (Lactococcus 20-92; 30a) is an equol-producing lactic acid bacterium isolated from the feces of healthy humans by Uchiyama et al. (30). This bacterium is spherical and Gram positive and is a strain of L. garvieae. The application of Lactococcus 20-92 in probiotics is advantageous because L. garvieae is not pathogenic or toxic to humans.To date, other bacterial strains that are capable of transforming daidzein to dihydrodaidzein or equol have been isolated (9,21,22,23,29,32,36,37). Daidzein is thought to be metabolized by human intestinal bacteria to equol or to Odesmethylangolensin via dihydrodaidzein and tetrahydrodaidzein (14,15,22,32); however, neither the enzymes involved in the metabolism of daidzein to equol nor even the metabolic pathway has been clarified fully for equol-producing bacteria.In this study, we purified an enzyme from Lactococcus 20-92 that assisted in the conversion of daidzein to dihydrodaidzein. Furthermore, we cloned the...