Flavonifractor plautii is an understudied species of the microbiota resident in the human gastrointestinal tract (GIT). The type strain of the species is recognised for its ability to cleave the C-ring of flavonoid polyphenols, such as quercetin. Polyphenols are plant secondary metabolites which have been shown to have beneficial effects on human health, both directly via the effects of these compounds on host physiology and metabolism, as well as indirectly, either via microbial biotransformations of the native compounds, and/or via growth effects on select members of the gut microbiota. Indeed, polyphenol-gut microbiota interactions are important to consider when studying the effects of polyphenols on host health. Previously, we isolated from the stool sample of a healthy Australian child strains taxonomically affiliated with F. plautii (SP1), using the metaparental mating methods developed in our lab. We investigated the effect of quercetin on the growth of strain SP1. Quercetin was added to brain-heart infusion (BHI) broths to give final concentrations of 0.5, 5.0, and 50 µM, and bacterial growth was monitored spectrophotometrically. There appeared to be little effects from added quercetin on either SP1 growth rate or yield, as compared to SP1 cultured using either BHI without added quercetin or BHI with carrier alone (DMSO). Based on these initial results, it appears that quercetin does not improve growth rate or yield of strain SP1 at the concentrations tested, which are reasonably within the range that might be expected to occur in the human gut. Our ongoing studies include biochemical validation of quercetin metabolism by strain SP1, including the sequencing and comparative analysis of the SP1 genome with the F. plautii type strain. We are also examining a wider range of candidate polyphenol-metabolising bacteria isolated from healthy Australian subjects, both in terms of their metabolic and immunomodulatory properties.