Equol is a metabolite of isoflavone daidzein and has an affinity to estrogen receptors. Although equol is produced by intestinal bacteria, the association between the status of equol production and the gut microbiota has not been fully investigated. The aim of this study was to compare the intestinal bacteria responsible for equol production in gut microbiota between equol producer and non-producer subjects regarding the intake of daidzein. A total of 1044 adult subjects who participated in a health survey in Hirosaki city were examined. The concentration of equol in urine was measured by high-performance liquid chromatography. The relative abundances of 8 bacterial species responsible for equol production in the gut microbiota was assessed using 16S rRNA amplification. There were 458 subjects identified as equol producers. The proportion of equol production status and the intake of daidzein increased with age. Daily intake of daidzein was larger in equol-producer. The intestinal bacteria, which convert daidzein to equol were present in both equol producers and non-producers. However, the relative abundance and the prevalence of Asaccharobacter celatus and Slackia isoflavoniconvertens were significantly higher in equol producers than those in equol non-producers. The intestinal bacteria that convert daidzein to equol are present in not only the equol producers but also in the non-producers. The daidzein intake is associated with the equol production status through an increase of A. celatus and S. isoflavoniconvertens in the gut microbiota.

Aims: To evaluate the influences of the accumulative effect of two consecutive rugby sevens matches (Sevens) on aspects of human neutrophil-related non-specific immunity. Methods: In seven players participating in the Japan Sevens, neutrophil reactive oxygen species (ROS) production capability and phagocytic activity were measured using flow cytometry, and serum opsonic activity (SOA) was assessed by measuring neutrophil ROS using the peak height of lucigenin-dependent chemiluminescence before and after two consecutive matches. Results: ROS showed no change immediately after the first match, and had significantly (P<0.05) increased 4 h later, but showed a decrease after the second match. Phagocytic activity showed no change immediately after the first match, but had significantly (P<0.01) decreased 4 h later, and showed a further decrease after the second match, although it was not significant. SOA significantly (P<0.01) increased after the first match, and still maintained its high 4 h later, but decreased after the second match. ROS production capability, phagocytic activity and SOA significantly (P<0.01) decreased after the second match. Conclusions: When rugby players play two consecutive Sevens matches, the exercise loading is thought to be hard, similar to that experienced during a marathon race and intensive or long training in a training camp, although the expected changes were not seen after the first match. Differences between after the first and the second matches may be due to the “cumulative effect”.

Background: Suppression of gastric acid by proton pump inhibitors is associated with the increase of Lactobacillus in human gut microbiota. Gastric acid secretion is also suppressed by Helicobacter pylori infection and following atrophic gastritis. However, few studies have examined the association between H. pylori infection and Lactobacillus species in gut microbiota particularly in Japan. Methods: A total of 1,123 adult subjects who participated in a health survey in Hirosaki City were studied. Infection of H. pylori was defined by both serum antibody and stool antigen test. The presence and the severity of atrophic gastritis were defined by the serum level of serum pepsinogens. Using 16S ribosomal RNA amplification from fecal samples, the relative abundance of Lactobacillus was calculated, and the composition ratio of each Lactobacillus species was surveyed. Results: The relative abundance of the Lactobacillus in H. pylori-infected subjects with severe atrophic gastritis was higher comparing with those in subjects with mild atrophic gastritis and without atrophic gastritis (0.591 vs 0.068% and 0.033%, respectively; p < 0.001) and also that of non-infected subjects (0.033%; p < 0.001). In H. pylori non-infected subjects, both gender and age were not associated with the relative abundance of Lactobacillus in fecal samples. The proportion of Lactobacillus salivarius was high in H. pylori-infected subjects while that of Lactobacillus acidophilus was high in non-infected subjects. Conclusion: Lactobacillus in human gut microbiota could be influenced by H. pylori infection and severity of atrophic gastritis in Japanese subjects.

Background: Although infection with Helicobacter pylori and subsequent atrophic gastritis modulate the gastric conditions, their relationship with the gut microbiota in ­Japanese population has not been clearly characterized. Methods: A cohort of 1,123 subjects who participated in a health survey was studied. Infection of H. pylori was defined by both serum antibody and stool antigen test. The presence and severity of atrophic gastritis were defined by serum levels of pepsinogens. The relative abundance of each bacterial species in fecal samples was calculated by using 16S ribosomal RNA amplification, and the composition ratios of bacterial taxa were evaluated using propensity score matching. Results: The abundance of 3 orders, 4 families, and 4 genera was significantly higher in H. pylori-infected subjects than in noninfected subjects (false discovery rate [FDR] <0.05). In H. pylori-infected subjects with severe atrophic gastritis, the abundance of the class Bacilli, order Lactobacillales, family Streptococcaceae, and genus Streptococcus was significantly higher than that in H. pylori-infected subjects without atrophic gastritis (FDR < 0.05). Conclusions: A significant increase in the relative abundance of several taxa was observed in gut microbiota of Japanese subjects with H. pylori infection. Among the subjects with severe atrophic gastritis, the increase in the genus Streptococcus is a remarkable characteristic.

Gut microbiomics is based on analysis of both live and dead cells in the stool. However, to understand the ecology of gut microbiota and their symbiotic relationships with hosts, spatial distribution of live bacteria must be examined. Here, we analyzed the live composition of luminal microbiota (LM) and mucosa-associated microbiota (MAM) in the ascending and descending colons and the rectums of 10 healthy adults and compared it with the total composition. The abundance of Lachnospiraceae in live LM decreased along the gut length and was significantly lower than that in total LM. Contrastingly, the abundance of Bacteroidaceae and Bifidobacteriaceae in live LM was higher than that in total LM, suggesting differences in death rate during gut migration. Live Enterobacteriaceae levels in MAM were significantly higher in rectum than in the ascending and descending colons and in LM. High-performance liquid chromatographic analysis of luminal bile acids revealed that 7α-dehydroxylation occurred towards the rectum. In live LM where a bile acid-inducible gene could be detected, 7α-dehydroxylation rates were higher than those in the group without the gene. Overall, we showed differences in live bacteria composition among three gut sites and between LM and MAM, highlighting the importance of understanding their spatial distribution.