Isolation of a Quercetin-metabolizing Bacterium 19 – 20 from Human Feces

Abstract

Much attention has been focused on the potential health-promoting effects of quercetin, a flavonoid that is metabolized by the intestinal microbiota. However, there are few reports on the intestinal bacteria that degrade quercetin. We isolated the quercetin-degrading bacterium strain 19 – 20 (Accession no: LC175305) from human feces. Based on comparative 16S rRNA gene sequence analysis, the bacterium exhibits 100% similarity to Clostridium orbiscindens (Accession no: Y18187). Quercetin degradation was observed to increase in a time-dependent manner when co-incubated with strain 19 – 20 in vitro; the majority of quercetin was degraded within 24 hr. Strain 19 – 20 quercetin degradation was inhibited by resveratrol. Co-incubation of quercetin and resveratrol significantly reduced strain 19 – 20 quercetin degradation. This is the first report of the inhibitory effect of resveratrol on quercetin degradation by intestinal bacteria.