Isolation and identification of a human intestinal bacterium capable of daidzein conversion

Abstract

Equol, which produced from daidzein (one of the principal isoflavones), is recognized to be the most resultful in stimulating an estrogenic and antioxidant response. The daidzein transformation was studied during fermentation of five growth media inoculated with feces from a healthy human, and a daidzein conversion strain was isolated. To enrich the bacterial population involved in daidzein metabolism in a complex mixture, fecal samples were treated with antibiotics. The improved propidium monoazide combined with the quantitative polymerase chain reaction (PMAxx-qPCR) assay showed that the ampicillin treatment of samples did result in a reduction of the total visible bacteria counts by 52.2% compared to the treatment without antibiotics. On this basis, the newly isolated rod-shaped, Gram-positive anaerobic bacterium, named strain Y11 (MN560033), was able to metabolize daidzein to equol under anaerobic conditions, with a conversion ratio (equol ratio: the amount of equol produced/amount of supplemented daizein) of 0.56 over 120 h. The 16S rRNA partial sequence of the strain Y11 exhibited 99.8% identity to that of Slackia equolifaciens strain DZE (NR116295). This study will provide new insights into the biotransformation of equol from daidzein by intestinal microbiota from the strain-level and explore the possibility of probiotic interventions.

Taxonomic distribution and evolutionary analysis of the equol biosynthesis gene cluster

“…This prevalence of Slackia_A and Adlercreutzia corroborates previous microbiome surveys, which have identified A. equolifaciens and Slackia_A isoflavoniconvertens strains as being significantly enriched in the guts of equol-producing humans [37,38]. Although equol-producing bacteria have been identified in multiple taxa outside of the Eggerthellaceae family, including the Bifidobacteria [29,39], Lactobacillus [4,28], Lactococcus [23], and Proteus [40] genera, no plausible equol gene clusters were seen in these groups based on the initial survey or subsequent searches using more liberal thresholds. The lack of homologous genes in these other taxa suggests that equol production is carried out by different sets of enzymes in these bacteria and highlights the need for additional sequencing and experimental work to understand equol production in these groups.…”

Association between lignan polyphenol bioavailability and enterotypes of isoflavone metabolism: A cross-sectional analysis

“…These bacteria may be shared in O-DMAP and EQP. In contrast, the gut bacteria, such as Slackia equolifaciens , that ultimately metabolize dihydrodaidzein to equol are likely to be different in O-DMAP compared with EQP [ 23 ].…”

Exploring substrate–microbe interactions: a metabiotic approach toward developing targeted synbiotic compositions

“… Substrate Product(/s) Effects Microbes Reference Amino acids L-alanyl-L-glutamine Prebiotic carbohydrates Butyric acid Enterocyte differentiation and survival Lipid and glucose homeostasis Lachnospiraceae Ruminococcaceae Bacteroidetes 31 , 97 Anthocyanins Protocatechuic acid Ferulic acid Phloroglucinaldehyde Glucose homeostasis, redox regulation Lactobacillus sp. 4 , 5 Daidzein Equol Cardiovascular, Estrogenic (FMD, lipid metabolism) Eggerthellaceae Lactococcus garvieae 20–92 62 , 63 Ellagitannins Ellagic acid Urolithin A Urolithin B Induction of autophagy Mitochondrial biogenesis Anti-inflammatory Gordonibacter Paraeggerthella Eggerthella 2 , 94 EPA DHA Specialized pro-resolving mediators (SPM) Resolution of inflammation Bacillus megaterium 97 Flavan-3-ols Phenyl-γ-valerolactones Anti-inflammatory Anti-tumorigenic Lactiplantibacillus plantarum IFPL935 Eggerthella lenta Adlercreutzia equolifaciens Flavonifractor plautii 73–75 Gliadin-epitopes Gluten Short peptides Amino acids Clearance of immunogenic or toxic epitopes ...…”

“…The gut microorganisms involved in the biotransformation of daidzein to equol are mostly from the Eggerthellaceae family, including Adlercreutzia equolifaciens , A. mucosicola , Slackia_A isoflavoniconvertens , Slackia_A equolifaciens , Enteroscipio sp000270285, and Lactococcus garvieae 20–92. 62 , 63 Other equol-producing bacteria have been identified in the Bifidobacteriaceae and Coriobacteriaceae family (including Asaccharobacter and Eggerthella ) and Clostridium genus. 64 , 65 However, investigations into the gut microbiome involved in the conversion of daidzein to ODMA are still limited.…”