Distribution Of Segmented Filamentous Bacteria And Investigation Of The Presentation Of Equol In Human Fecal Samples

The human intestine is colonized by numerous microbiota, which forms a complex microbial community that deeply affects the human health and physiological status. We first investigated the distribution of SFB in human feces and then determined the concentrations of daidzein and equol in human fecal samples. Finally, the relationship between the production level of equol and the bacterial community of human fecal samples was studied.Segmented filamentous bacteria (SFB) are indigenous gut commensal bacteria. The aim of this study was to investigate the distribution of SFB in humans. Gut contents from251humans,92mice and72chickens were collected for bacterial genomic DNA extraction and subjected to SFB16S rRNA-specific PCR detection. The results showed SFB colonization in human intestine with a age-dependent manner. The populations peaked in the infants aged6to24months old and disappeared completely when the infants reached3years old. The current result indicated that SFB may involve in the development of human immune system because it only detected at the beginning of age.The second part of study is regarding the distribution of equol in human feces. Equol is an important daidzein metabolite bio-transformed by the intestinal bacteria from a major component of isoflavones, dadzein.Since there have few information regarding the relationship between equol generation and the intestinal microflora structure, in current study we first investigated the distribution and concentration of the daidzein and equol in human fecal samples by HPLC method. One hundreds and twenty five human fecal samples were collected from the Hangzhou area. HPLC analysis showed a strong relationship between the age and the levels of equol in the feces, with the highest concentration observed in the age group of40-50years old. We did not observe a strong correlation between the level of equol and gender.The second part of work was to study the relationship between the equol-producing level and the bacterial community by PCR-DGGE method. PCR-DGGE results demonstrated that there was no correlation between the level of equol and the particular structure of the bacterial community in human feces.We then tried to enrich and isolate the human intestinal bacteria that were capable of transforming daidzein to equol. Four growth mediums, BHI, VI, VL and M9were inoculated with human fecal samples inside the anaerobic chamber and daidzein was used as the sole carbon source. The concentration of equol was detected in every6hours. HPLC results demonstrated that BHI broth was the best medium to enrich the equol producing bacteria. The highest concentration of equol reached to38.8μg/ml in BHI broth after24hours incubation.To summery, current study demonstrated that age is a key factor affecting the microbiota community structures, which led to generate different biological and physiological properties.