Adlercreutzia equolifaciens gen. nov., sp. nov., an equol-producing bacterium isolated from human faeces, and emended description of the genus Eggerthella

Abstract

Adlercreutzia equolifaciens gen. nov., sp. nov., an equol-producing bacterium isolated from human faeces, and emended description of the genus Eggerthella Nine strains capable of metabolizing isoflavones to equol were isolated from human faeces. Four of the strains were characterized by determining phenotypic and biochemical features and their phylogenetic position based on 16S rRNA gene sequence analysis. These strains were related to Eggerthella sinensis HKU14 T with about 93 % 16S rRNA gene sequence similarity; they were asaccharolytic, obligately anaerobic, non-spore-forming, non-motile and Gram-positive coccobacilli. In enzyme activity tests, arginine dihydrolase, arginine and leucine arylamidases were positive but nitrate reduction, urease and b-glucosidase were negative. The major menaquinone was DMMK-6 (dimethylmenaquinone-6), while that of members of the genus Eggerthella was MMK-6 (methylmenaquinone-6). Furthermore, the cell-wall peptidoglycan type of these strains was A1c, while that of members of the genus Eggerthella was A4c. On the basis of these data, a new genus, Adlercreutzia gen. nov., is proposed with one species, Adlercreutzia equolifaciens sp. , 2006). We isolated nine strains capable of metabolizing isoflavones to equol from human faeces. Seven of these strains could metabolize daidzein via dihydrodaidzein to equol, while the other two isolates could metabolize only dihydrodaidzein to equol. These strains were divided into four groups by 16S rRNA gene sequence analysis. Representative strains selected from each group were asaccharolytic, obligately anaerobic, non-spore-forming, non-motile and Gram-positive coccobacilli. Although these strains were genetically related to the genus Eggerthella, they did not belong to the genera Eggerthella, Slackia or Denitrobacterium from 16S rRNA gene sequence analysis.The presence of dimethylmenaquinone-6 (DMMK-6) as the predominant menaquinone of these strains is unique. Furthermore, the cell-wall peptidoglycan type of these strains was A1c, while that of members of the genus Eggerthella was A4c.Strains FJC-A10, FJC-A161, FJC-B9 T , FJC-B12, FJC-B15, FJC-B19, FJC-B20, FJC-D47 and FJC-D53 were cultivated for 3 days at 37 u C on BL agar (Nissui) with 5 % (v/v) horse blood. Coriobacterium glomerans JCM 10262 T was cultivated for 2 days at 30 u C on GAM agar (Nissui). Detailed menaquinone and fatty acid profiles of representative strains and related type strains and minimum-evolution and maximumparsimony 16S rRNA gene sequence-based trees are available as supplementary material with the online version of this paper.

Isolation of a Human Intestinal Bacterium Capable of Daidzein and Genistein Conversion

“…While formation of equol from daidzein via dihydrodaidzein is catalyzed by several bacterial species (16,17,20,21,40), the corresponding conversion of genistein to 5-hydroxy-equol has been demonstrated for only two strains, Mt1B8 and DZE (13,17). This may be due to the fact that genistein transformation has not been investigated.…”

“…Using the same conditions, the ability of the phylogenetically related Slackia species to convert daidzein and genistein was tested. S. faecicanis and S. heliotrinireducens did not transform any of the isoflavones within 96 h. Only S. exigua completely converted daidzein and genistein (50 M each), respectively, within 96 h. Whereas O-desmethylangolensin was formed from daidzein (16), no metabolites were detected following genistein degradation.…”

“…Lower values of sequence identity were observed for strain HE8 and the equol-forming species Adlercreutzia equolifaciens (90.2%), Eggerthella sp. strain Julong 732 (89.9%) and strain DZE (87.6%) from human feces, Asaccharobacter celatus (90.1%) from rat cecum, and strain Mt1B8 from mouse intestine (88.8%), all of which affiliate within the Coriobacteriaceae (13,16,17,20,21,36). All of these bacterial strains produce equol from daidzein, with the exception of Eggerthella sp.…”

Counts of Slackia sp. strain NATTS in Intestinal Flora are Correlated to Serum Concentrations of Equol both in Prostate Cancer Cases and Controls in Japanese Men

“…Other several strains converting daidzein into equol have already been found by cultivation in vitro from human intestinal bacteria. For instance, Enterococcus faecium EPI1, Finegoldia magna EPI3 and Lactobacillus mucosae EPI2 (Decroos et al, 2005), Aldercreutzia equolifaciens (Maruo et al, 2008), Eggerthella sp. YY7918 (Yokoyama et al, 2008), Slackia sp.…”

Butyricimonas synergistica gen. nov., sp. nov. and Butyricimonas virosa sp. nov., butyric acid-producing bacteria in the family 'Porphyromonadaceae' isolated from rat faeces

“…pneumoniae and Bifidobacterium infantis, were found to be capable of hydrolysing (2)-epigallocatechin gallate to yield (2)-epigallocatechin (EGC) and gallic acid. Furthermore, we isolated Adlercreutzia equolifaciens (Maruo et al, 2008) strain MT4s-5, which is capable of catabolizing EGC to 1- (39,49,59-trihydroxyphenyl)-3-(29,49,69-trihydroxyphenyl) propan-2-ol (A. Takagaki, D. Arai, S. Ishikawa & F. Nanjo, unpublished data). Subsequent research revealed that A. equolifaciens strain MT4s-5 could convert 1- (39,49,59-trihydroxyphenyl)-3-(29,49,69-trihydroxyphenyl) propan-2-ol to 1-(39,59-dihydroxyphenyl)-3-(29,49,69-trihydroxyphenyl) propan-2-ol in the presence of three types of symbiotic bacterium, namely Escherichia coli and two isolates designated MT01 T and MT12 T (unpublished data).…”