Bacteroides intestinalis

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Higher order taxa

Bacteria; Bacteroidetes; Bacteroidia; Bacteroidales; Bacteroidaceae; Bacteroides




Bacteroides intestinalis are rod shaped, gram negative, anaerobic cells. They are not motile, nor do they form spores. The cells occur singly (approximately 0.8 µm wide and 1-5 µm long), but after approximately two days, transluscent-whitish colonies (raised, circular, and 1-3 mm in diameter) will form. They grow optimally at 37 degrees Celsius, consistent with human body temperature. Monosaccharides, disaccharides, and polysaccharides such as glucose, lactose, sucrose, maltose, xylose, arabinose, cellobiose, mannose, raffinose and rhamnose are metabolized creating an acid as a biproduct.


Bacteria was obtained from human feces, and polyamine production was tested by growing the acquired gut bacteria on a polyamine deficient media. This permitted the isolation of five strains able to synthesize polyamines. One of the five isolated species was Bacteroides intestinalis, a novel species, discovered and named in 2006. Biochemical tests revealed this species is most closely related to Bacteroides uniformis and Bacteroides helcogenes.


Polyamines are organic molecules needed for animal cell growth and differentiation. Bacteria can create polyamines by decarboxylation of the amino acids lysine, arginine, and orthinine. Bacteroides are known to produce polyamines, specifically spermidine. Spermidine is a poly-cationic polyamine used in many biological mechanisms. It is found in nearly all tissues associated with nucleic acids, and is thought to stabilize DNA, and other nucleic acid structures as well as membranes. In animals, polyamines are ubiquitous, and the origin of the polyamines can be due to internal or external factors. Gut bacteria is thought to be a major contributor.


Bacteroides intestinalis, a member of the phylum Bacteroidetes, was first discovered in human feces. Gut microbes in humans outnumber somatic and germline cells by a factor of ten. There are trillions of microbes present, and in healthy individuals, once a species is present, it stays for decades or longer. Some microbiologists believe that sequencing and monitoring the gut microbiome from year to year may be helpful in the future of medicine. It is hypothesized that gut bacteria contribute to the pathophysiology of obesity. Bacteriodetes are prevalent in gut bacteria and tend to make up a higher percentage of the gut bacteria in healthy weight people compared to obese people.


Bakir, M.A., Kitahara, M., Sakamoto, M., Matsumoto, M., Benno, Y. “Bacteroides intestinalis sp. nov., isolated from human faeces.” International Journal of Systematic and Evolutionary Biology. January 2006 vol. 56 p.151-154

Bakir, M.A., Kitahara, M., Sakamoto, M., Matsumoto, M., Benno, Y. “Bacteroides finegoldii sp. nov., isolated from human faeces.” International Journal of Systematic and Evolutionary Biology.’’ May 2006. vol. 56 no. 5 p. 931-935

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Yong, E. “Gut Microbes for Life.” TheScientist; Exploring life, inspiring innovation. July 2014. (accessed March 12, 2014).

Ismail, N.A., Ragab, S.H., ElBaky, A.A., Shoeib, A.R.S., Alhosary, Y., Fekry, D. National Center for Biotechnology Information. “Frequency of Firmicutes and Bacteroidetes in gut microbiota in obese and normal weight Egyptian children and adults” Arch Med Sci. Jun 2011; 7(3): p.501–507. Published online Jul 11, 2011. doi: 10.5114/aoms.2011.23418

Edited by (Amanda Hayes), student of Rachel Larsen at the University of Southern Maine