Panax ginseng (family Araliaceae) which contains
ginsenoside Rb1 as a main constituent is traditionally used as a remedy for
cancer,
inflammation, stress, and ageing. The
ginsenoside Rb1 in orally administered ginseng is metabolized to bioactive compounds by gut microbiota before their absorptions to the blood. However, its metabolizing activities in individuals are significantly different as we previously demonstrated. Here, we selected 5 samples with fecal activity potently metabolizing
ginsenoside Rb1 to
compound K (FPG; metabolic activity, 0.058±0.029 pmol/min/mg) and 5 samples with fecal activity non-metabolizing
ginsenoside Rb1 to
compound K (FNG) from a pool of 100 subjects investigated in a previous study and analyzed fecal microbiota by
16S rRNA gene pyrosequencing. Taxonomy-based analysis showed that the population levels of Firmicutes and Proteobacteria in FPG were lower than in FNG, but those of Bacteroidetes and Tenericutes in FPG were higher than in FNG. At the genus level, the population levels of Clostridiales_uc_g, Oscillibacter, Ruminococcus, Holdemania, and Sutterella in FPG were significantly higher than in FNG, but that of Leuconostoc in FPG was lower than in FNG. The population levels of Bacteroides and Bifidobacterium, which potently metabolizes
ginsenoside Rb1 to
compound K were dramatically increased in FPG. The gut microbiota compositions of FPG and FNG were segregated on PCO2 by Principal Coordinate Analysis. Intestinal bacterial metabolism of ginseng, particularly
ginsenoside Rb1, may be dependent on the composition of gut microbiota, such as Ruminococcus spp., Bacteroides spp. and Bifidobacterium spp.