Temperate bacteriophages infecting the mucin-degrading bacterium Ruminococcus gnavus from the human gut

Abstract

Ruminococcus gnavus is a prevalent gut microbe reported to occur in higher abundance among individuals with inflammatory bowel disease (IBD). This study reports the isolation and characterization of six bacteriophages (phages) isolated from human fecal material and environmental samples that infect this species. Isolated phages have a siphovirus morphology, with genomes ranging between 36.5 and 37.8 kbp. Genome analysis indicates that the phages have a temperate lifestyle, which was confirmed by their ability to form lysogens on their host bacterial species. In contrast to the finding that phages lyse their host in liquid medium, results from a mouse trial indicate these phages can co-exist with the host bacterium in the gut without causing a significant reduction of R. gnavus . The bacterial counts in the feces of phage-treated mice did not significantly differ in the presence of phage. Furthermore, analysis of publicly available gut virome sequence data indicates a high abundance of these phages among individuals suffering from IBD. This work provides the first insight into how phages interact with R. gnavus in the human gut microbiome.

The Role of Bacteriophages in the Gut Microbiota: Implications for Human Health

“…The bacteria Ruminococcus gnavus, a Gram-positive anaerobe, is also widely prevalent in the microbiota of humans with inflammatory bowel disease conditions due to Crohn's disease [143]. Buttimer et al [144] isolated, characterized, and analyzed six phages that infect the R. gnavus JCM 6515T strain. Although no significant decrease in the bacterial count was reported post-phage administration, the study provided insight into two significant mechanisms through which phages interact with R. gnavus in the human gut microbiome.…”