Cultured Representatives of Two Major Phylogroups of Human Colonic Faecalibacterium prausnitzii Can Utilize Pectin, Uronic Acids, and Host-Derived Substrates for Growth

Abstract

ABSTRACTFaecalibacterium prausnitziiis one of the most abundant commensal bacteria in the healthy human large intestine, but information on genetic diversity and substrate utilization is limited. Here, we examine the phylogeny, phenotypic characteristics, and influence of gut environmental factors on growth ofF. prausnitziistrains isolated from healthy subjects. Phylogenetic analysis based on the 16S rRNA sequences indicated that the cultured strains were representative ofF. prausnitziisequences detected by direct analysis of fecal DNA and separated the available isolates into two phylogroups. MostF. prausnitziistrains tested grew well under anaerobic conditions on apple pectin. Furthermore,F. prausnitziistrains competed successfully in coculture with two other abundant pectin-utilizing species,Bacteroides thetaiotaomicronandEubacterium eligens, with apple pectin as substrate, suggesting that this species makes a contribution to pectin fermentation in the colon. ManyF. prausnitziiisolates were able to utilize uronic acids for growth, an ability previously thought to be confined toBacteroidesspp. among human colonic anaerobes. Most strains grew onN-acetylglucosamine, demonstrating an ability to utilize host-derived substrates. All strains tested were bile sensitive, showing at least 80% growth inhibition in the presence of 0.5 μg/ml bile salts, while inhibition at mildly acidic pH was strain dependent. These attributes help to explain the abundance ofF. prausnitziiin the colonic community but also suggest factors in the gut environment that may limit its distribution.