Karel Decroos

Isolation and characterisation of an equol-producing mixed microbial culture from a human faecal sample and its activity under gastrointestinal conditions.

Only about one third of humans possess a microbiota capable of transforming the dietary isoflavone daidzein into equol. Little is known about the dietary and physiological factors determining this ecological feature. In this study, the in vitro metabolism of daidzein by faecal samples from four human individuals was investigated. One culture produced the metabolites dihydrodaidzein and O-desmethylangolensin, another produced dihydrodaidzein and equol. From the latter, a stable and transferable mixed culture transforming daidzein into equol was obtained. Molecular fingerprinting analysis (denaturing gradient gel electrophoresis) showed the presence of four bacterial species of which only the first three strains could be brought into pure culture. These strains were identified as Lactobacillus mucosae EPI2, Enterococcus faecium EPI1 and Finegoldia magna EPI3, and did not produce equol in pure culture. The fourth species was tentatively identified as Veillonella sp strain EP. It was found that hydrogen gas in particular, but also butyrate and propionate, which are all colonic fermentation products from poorly digestible carbohydrates, stimulated equol production by the mixed culture. However, when fructo-oligosaccharides were added, equol production was inhibited. Furthermore, the equol-producing capacity of the isolated culture was maintained upon its addition to a faecal culture originating from a non-equol-producing individual.

In vitro and in vivo assessment of intraintestinal bacteriotherapy in chronic kidney disease.

Chronic kidney disease may progress to end-stage renal disease, which requires dialysis or kidney transplantation. No generally applicable therapies to slow progression of renal disease are available. Bacteriotherapy affords a promising approach to mitigate uremic intoxication by ingestion of live microbes able to catabolize uremic solutes in the gut. The present study evaluates the nonpathogenic soil-borne alkalophilic urease-positive bacterium Sporosarcina pasteurii (Sp) as a potential urea-targeted component for such “enteric dialysis” formulation. Data presented herein suggest that Sp survives through exposure to gastric juice retaining the ability to hydrolyze urea. In vitro, 109 cfu (colony forming units) of Sp removed from 21 ± 4.7 mg to 228 ± 6.7 mg urea per hour, depending on pH, urea concentration, and nutrient availability. Beneficial effects of Sp on fermentation parameters in the intestine were demonstrated in vitro in the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) inoculated with fecal microbiota. Enumeration of marker organisms suggested that presence of Sp does not disturb microbial community of the SHIME. Additionally, a pilot study in 5/6th nephrectomized rats fed 109 cfu of live Sp daily throughout the study demonstrated that the tested regimen reduced blood urea-nitrogen levels and significantly prolonged the lifespan of uremic animals.