R. gnavus

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Classification

Bacteria (Domain); Bacillota (Phylum); Clostridia (Class); Eubacteriales (Order); Lachnospiraceae (Family); Mediterraneibacter (Genus)

File:Ruminococcusgnavus.jpg

Stained sample of plated Ruminococcus gnavus. Image credit:

Species

File:Ruminococcusgnavus.jpg Stained sample of plated Ruminococcus gnavus. Image credit: Ruminococcus gnavus Description and Significance Ruminococcus gnavus is a Gram-positive obligate anaerobe bacterium discovered first in the human gastrointestinal tract. Despite its name it is actually a part of the genus Mediterraneibacter, although retaining its Ruminococcus name for study purposes. R. gnavus is considered a part of the normal human gut microbiome in children and adults. It has been suggested that it has a role in priming the gut microbiota in association with standard weight gain velocity in infants. Ruminococcus gnavus is one of few micorbiota bacterium that persists at a consistent level from infancy to throughout adulthood. Studies have shown that R.gnavus is a key biomarker of health and diseases with certain immune/metabolic properties, making it an important bacterium to understand. Genome Structure Ruminococcus gnavus contains circular chromosomes containing 77 RNA coding genes, 3345 protein coding genes, and 3549191 nucleotides. R.gnavus was found to have a mean genome size of 3.46±0.34 Mbp, with a mean G+C conctent of 42.73±0.33 mol%. R.gnavus' pan-core genome analysis revealed a predicted 28,072 genes, with the core genes making up 3.74% (1051) of that. The function of the majority of its core genes are not known. Cell Structure, Metabolism and Life Cycle Interesting features of cell structure; how it gains energy; what important molecules it produces. Ecology and Pathogenesis There are a multitude of studies that show a large positive association between Crohn's disease and Ruminococcus gnavus populations. R. gnavus populations skyrocket during flare ups in Crohn's disease patients. R. gnavus produces an inflammatory glucorhamnan polysaccharide that triggers the production of inflammatory cytokines. Patients experiencing Crohn's disease and an increase in R. gnavus experience symptoms such as abdominal pain, diarrhea, and bloody stool. Patients experiencing extreme symptoms may face inflammation of the eyes, skin, and spine. In order to survive and thrive within the human gut, R.gnavus evolved mechanisms to adapt to their environment. These are labeled "microbial colonization factors". Ruminococcus gnavus produce antimicrobial peptides called bacteriocins to inhibit the growth of other potential competitors. It has also evolved to produce a range of carbohydrate-active enzymes, allowing them to metabolize complex carbohydrates. References Abdugheni, R., Liu, C., Liu, F.-L., Zhou, N., Jiang, C.-Y., Liu, Y., Li, L., Li, W.-J., & Liu, S.-J. (2023, July 24). Comparative genomics reveals extensive intra-species genetic divergence of the prevalent gut commensal Ruminococcus Gnavus. microbiologyresearch.org. https://www.microbiologyresearch.org/content/journal/mgen/10.1099/mgen.0.001071 Crost, E. H., Coletto, E., Bell, A., & Juge, N. (2023). Ruminococcus gnavus: Friend or foe for human health. FEMS Microbiology Reviews, 47(2). https://doi.org/10.1093/femsre/fuad014 Henke, M. T., Kenny, D. J., Cassilly, C. D., Vlamakis, H., Xavier, R. J., & Clardy, J. (2019, June 25). ruminococcus gnavus, a member of the human gut microbiome associated with crohn’s disease, produces an inflammatory polysaccharide. Proceedings of the National Academy of Sciences of the United States of America. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6601261/ Kegg Genome: Ruminococcus Gnavus. (2020). https://www.genome.jp/kegg-bin/show_organism?org=T06719 Author Page authored by Chris Blackwell, student of Prof. Bradley Tolar at UNC Wilmington.