Use of high throughput amplicon sequencing and ethidium monoazide dye to track microbiota changes in an equol-producing menopausal woman receiving a long-term isoflavones treatment.

Lucía Guadamuro,M Andrea Azcárate-Peril,Baltasar Mayo,Susana Delgado,Rafael Tojo

doi:10.3934/microbiol.2019.1.102

Lucía Guadamuro, M Andrea Azcárate-Peril + Show 3 more

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https://doi.org/10.3934/microbiol.2019.1.102

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This work describes the impact of long term consumption of an isoflavone-rich dietary daily supplement on the composition and diversity of the faecal microbiota of a menopausal, equol-producing woman. Sequencing of 16S rDNA amplicons was performed on faecal samples taken at 0, 1, 3 and 6 months of treatment. Additionally, and for comparative purposes, ethidium monoazide (EMA) was used to avoid detection of DNA from dead bacteria. Members of two genera of the family Coriobacteriaceae (Eggerthella and Collinsella) were found in greater proportions at all sampling points during isoflavone supplementation. Different genera of the family Ruminococcaceae (e.g., Ruminococcus and Faecalibacterium), as well as members of the family Lachnospiraceae (Coprococcus) also underwent significant increases. For this last genus a positive correlation with the levels of equol excretion in urine was found. Currently bacterial strains known to be involved in isoflavone metabolism and equol production have been assigned to these taxa. The use of EMA dye allowed us to unravel those bacterial gut linages (e.g., Lachnospiraceae) that were more susceptible to damage. Our study contributes to the identification of microorganisms possibly involved in the production of isoflavone-desirable metabolites (such as equol), which could ultimately be isolated and further used as probiotics by people who cannot naturally benefit from isoflavones.

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Isoflavones are plant-derived phytoestrogens, belonging to the chemical family of polyphenols, present in especially large amounts in soy and soy-derived products
The full range of intestinal bacteria involved in equol formation remains unknown [5,11], most of those recognised as equol-producers to date are members of the family Coriobacteriaceae [12]
In the urine samples of the woman of this study, equol concentration increased from 9 nM at baseline to 1,143 nM at T1 (Figure 1 A)

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Introduction

Isoflavones are plant-derived phytoestrogens, belonging to the chemical family of polyphenols, present in especially large amounts in soy and soy-derived products. Isoflavone glycosides need to be transformed into isoflavone aglycones via enzymes produced by the intestinal tissue and gut microorganisms [7]. Some intestinal bacteria metabolize isoflavone aglycones into other active compounds, such as equol [7,8]. Formed from the aglycone daidzein, equol is the isoflavone-derived metabolite with the strongest oestrogenic and antioxidant activities [9]. Only 25–30% of Western individuals have been reported to be able to convert daidzein into equol [10] and they could be the ones that harbour the appropriated gut microbiota required for its bioconversion. The full range of intestinal bacteria involved in equol formation remains unknown [5,11], most of those recognised as equol-producers to date are members of the family Coriobacteriaceae [12]

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