What is Bacteroides thetaiotaomicron?

June 12, 2023 3 min read

What is Bacteroides thetaiotaomicron?

Bacteroides thetaiotaomicron, commonly known as B. theta, is a Gram-negative, anaerobic bacterium that inhabits the human gut. It is a member of the Bacteroidetes phylum and is one of the most abundant bacterial species found in the human intestinal microbiota. B. theta plays an important role in maintaining gut health by breaking down complex dietary polysaccharides and producing short-chain fatty acids (SCFAs). Additionally, B. theta has been associated with various health benefits such as promoting anti-inflammatory responses, regulating the immune system, and protecting against certain diseases.

Here are some key points about B. theta:

  • Dietary polysaccharide degradation: B. theta is known for its ability to break down complex dietary polysaccharides, such as inulin and pectin, that cannot be digested by human enzymes. These polysaccharides serve as a source of energy for the bacteria and help to maintain the health of the gut microbiota.
  • Short-chain fatty acid production: As B. theta degrades dietary polysaccharides, it produces short-chain fatty acids (SCFAs) as a byproduct. SCFAs are important energy sources for colonocytes and can also regulate immune function, promote anti-inflammatory responses, and improve gut barrier function.
  • Anti-inflammatory responses: B. theta has been shown to promote anti-inflammatory responses in the gut by inducing regulatory T cells and promoting the production of anti-inflammatory cytokines. This may help to protect against inflammatory bowel diseases such as ulcerative colitis and Crohn's disease.
  • Immune system regulation: B. theta has been shown to modulate the immune system by promoting the development of immune cells and regulating the production of immune mediators. This may help to protect against autoimmune diseases and infections.
  • Protection against certain diseases: Studies have suggested that B. theta may play a role in protecting against certain diseases such as colon cancer, metabolic disorders, and cardiovascular diseases.

However, in certain cases, an overgrowth of B. thetaiotaomicron can be associated with certain health conditions. One such condition is inflammatory bowel disease (IBD). Studies have shown that individuals with IBD have higher levels of B. thetaiotaomicron in their gut microbiome than healthy individuals. Additionally, B. thetaiotaomicron has been shown to increase the production of pro-inflammatory cytokines in the gut, which can exacerbate inflammation in individuals with IBD.

Another potential negative effect of B. thetaiotaomicron overgrowth is its ability to produce a toxin called fragilysin. Fragilysin has been shown to damage the intestinal barrier and increase gut permeability, leading to a variety of health issues including inflammation, metabolic disorders, and even neurological disorders.

Research on B. theta is still ongoing, and scientists continue to explore the mechanisms by which this bacterium contributes to gut health. Understanding the role of B. theta in the gut microbiota may lead to the development of new therapeutic strategies for gut-related diseases.

 

References:

  1. Belenguer A, Duncan SH, Calder AG, Holtrop G, Louis P, Lobley GE, Flint HJ. Two routes of metabolic cross-feeding between Bifidobacterium adolescentis and butyrate-producing anaerobes from the human gut. Appl Environ Microbiol. 2006 May;72(5):3593-9. doi: 10.1128/AEM.72.5.3593-3599.2006. PMID: 16672523; PMCID: PMC1472386.
  2. Cao Y, Shen J, Ran ZH. Association between Faecalibacterium prausnitzii reduction and inflammatory bowel disease: a meta-analysis and systematic review of the literature. Gastroenterol Res Pract. 2014;2014:872725. doi: 10.1155/2014/872725. Epub 2014 Aug 28. PMID: 25247191; PMCID: PMC4167942.
  3. Hooper LV, Littman DR, Macpherson AJ. Interactions between the microbiota and the immune system. Science. 2012 Jun 8;336(6086):1268-73. doi: 10.1126/science.1223490. PMID: 22674334; PMCID: PMC3601187.
  4. Martens EC, Lowe EC, Chiang H, Pudlo NA, Wu M, McNulty
  5. Machiels, K., Joossens, M., Sabino, J., De Preter, V., Arijs, I., Eeckhaut, V., ... & Vermeire, S. (2014). A decrease of the butyrate-producing species Roseburia hominis and Faecalibacterium prausnitzii defines dysbiosis in patients with ulcerative colitis. Gut, 63(8), 1275-1283.
  6. Wu, H. J., Wu, E., & Chen, L. (2017). Apigenin attenuates colonic inflammation and tumorigenesis by inhibiting the IRAK1/TAK1/NF-κB signaling pathway in IBD. Molecular carcinogenesis, 56(1), 197-207.
  7. Duboc, H., & Rainteau, D. (2014). Role of the gut microbiota in the pathogenesis of inflammatory bowel disease. World journal of gastroenterology, 20(44), 17293-17308.
  8. Zhang, Y., Limaye, P. B., Renaud, H. J., Klaassen, C. D., & Desai, D. H. (2017). Ontogeny of hepatic energy metabolism genes in mice as revealed by RNA-sequencing. PloS one, 12(4), e0174541.


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