Flavonifractor plautii

Flavonifractor plautii is a bacterium of the monotypic genus Flavonifractor in the family Oscillospiraceae.

History
This species was originally placed in the genus Fusobacterium by S. Seguin in 1928, only to be then recategorized to Fusocillus in 1938 by A.R. Prevot. This name lasted until 1962, when M. Sebald renamed the species Zuberella plauti. In 1928, Skerman VBD et al. called this species Fusobacterium plauti in their “Approved Lists of Bacterial Names” published in the International Journal of Systematic Bacteriology (now known as the International Journal of Systematic and Evolutionary Microbiology). In 1982, Hofstad, T. and Assjord, P. published in this same journal, officially naming the species Eubacterium plautii. Nine years later, in 1991, Winter J et al. published an article in the Int. J. Cyst. Bacteriol. describing this bacterium’s ability to cleave flavonoids, referring to it as its most recent basionym Clostridium orbiscindens. Finally in 2010, Carlier JP et al.proposed to call this species Flavonifractor plautii. Cells are described as straight or slightly curved rods, 2-10 microns long, and occur singly or in pairs. Strains have been isolated from human feces, blood, intra-abdominal pus, and infected soft tissues in humans.

Genetics and Function
Flavonifractor plautii has a genome consisting of a single circular chromosome with 3,985,392 base pairs, with a G+C content of 60.9%. The genome is predicted to contain 3 complete sets of rRNA genes, 63 tRNA genes, and 3,764 protein-coding sequences. This bacterium is an obligate anaerobe that is capable of cleaving the C-ring found in flavonoids. Flavonifractor plautii is highly prevalent in the human gastrointestinal tract, and is known to be a proficient producer of butyrate.

Clinical Relevance
In 2019, Gupta et al. found F. plautii to be associated with colorectal cancer (CRC) from a cohort of 30 CRC patients and 30 healthy controls. Their hypothesis stated that the degradation of beneficial anticarcinogenic flavonoids, antioxidants such as quercetin, may be contributing to the cancer. In another assessment, Liu et al. found Flavonifractor plautii to be significantly enriched in major depressive disorder (MDD) from a cohort of 90 American young adults (43 with MDD, 47 healthy). Armstrong et al. found preferential binding of IgG from Crohn’s disease patients to F. plautii as compared to non-IBD and ulcerative colitis derived microbes. They also demonstrated that F. plautii had invasive potential in vitro using a fluorescence microscopy based assay using intestinal epithelial cells in culture.