Disease and microbiota in the gut

Microbiome: all the bacteria, good and bad, that live within and on the surface of the body.

There are some studies that suggest an imbalanced microbiome, either on the skin or in the gut, is the cause of some disease, including autoimmune diseases like diabetes, rheumatoid arthritis, muscular dystrophy, multiple sclerosis, fibromyalgia. There are also studies that show correlation of an incorrect microbiome to obesity.

This study by Ridaura (2013) shows that mice without certain Bacterioides bacteria tend to be obese. It also has some interesting graphs.This study shows that people who are obese tend to have a higher ratio of Firmicutes:Bacteroidetes bacteria. That is, higher Firmicutes and less Bacteroidetes.

This study tries to find a correlation between diabetes type 1 and gut bacteria.

Scientists even divide people into 3 groups based on their gut bacteria composition.

Systemic antibiotics can have a negative impact on these gut bacteria. Some people recover their healthy ratio of bacteria, others never do. And it is suspected that imbalanced bacteria cause other autoimmune problems. So avoid antiobiotics, especially systemic ones.

For more fun sites try these:

• What germs are on your cellphones and shoes? Link. 

Sources

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2. Human Microbiome Project. Studying microbiomes to understand their role in human health. They also have the genomes of reference strains of bacteria. Link here.
3. Giongo, A., Gano, K. A., Crabb, D. B., Mukherjee, N., Novelo, L. L., Casella, G., … Triplett, E. W. (2011). Toward defining the autoimmune microbiome for type 1 diabetes. The ISME Journal, 5(1), 82–91. http://doi.org/10.1038/ismej.2010.92.  
4. Grice EA, Kong HH, Conlan S, Deming CB, Davis J, Young AC, NISC Comparative Sequencing Program, Bouffard GG, Blakesley RW, Murray PR, Green ED, Turner ML, Segre JA; Kong; Conlan; Deming; Davis; Young; Bouffard; Blakesley; Murray; Green; Turner; Segre (2009). "Topographical and Temporal Diversity of the Human Skin Microbiome". Science 324 (5931): 1190–2. Bibcode:2009Sci...324.1190G. doi:10.1126/science.1171700. PMC 2805064. PMID 19478181. NIH full study.
5. Home Microbiome site. Link. "The Home Microbiome Study is lead by PI Jack Gilbert, postdoc Daniel Smith, and technician Jarrad Hampton-Marcell at Argonne National Laboratories, and funded by the Alfred P. Sloan Foundation. This study is working in collaboration with MicroBE.net and the Earth Microbiome Project to bring together microbial samples from as many environments as possible in order to understand how microbial community structure is shaped by environmental factors."
6. Ridaura VK, Faith JJ, Rey FE, Cheng J, Duncan AE, Kau AL, Griffin NW, Lombard V, Henrissat B, Bain JR, Muehlbauer MJ, Ilkayeva O, Semenkovich CF, Funai K, Hayashi DK, Lyle BJ, Martini MC, Ursell LK, Clemente JC, Van Treuren W, Walters WA, Knight R, Newgard CB, Heath AC, Gordon JI. Gut microbiota from twins discordant for obesity modulate metabolism in mice. Science. 2013 Sep 6;341(6150):1241214. doi: 10.1126/science.1241214. PubMed PMID: 24009397; PubMed Central PMCID: PMC3829625. NIH abstract. This one has fascinating charts.
7. Turnbaugh, P. J., Hamady, M., Yatsunenko, T., Cantarel, B. L., Duncan, A., Ley, R. E., … Gordon, J. I. (2009). A core gut microbiome in obese and lean twins. Nature, 457(7228), 480–484. http://doi.org/10.1038/nature07540. Full study at NIH. 
8. Wikipedia page for "microbiota". Many studies here.
9. Turnbaugh PJ, Ley RE, Mahowald MA, Magrini V, Mardis ER, Gordon JI. An obesity-associated gut microbiome with increased capacity for energy harvest. Nature. 2006 Dec 21;444(7122):1027-31. PubMed PMID: 17183312 NIH abstract. "Comparisons of the distal gut microbiota of genetically obese mice and their lean littermates, as well as those of obese and lean human volunteers have revealed that obesity is associated with changes in the relative abundance of the two dominant bacterial divisions, the Bacteroidetes and the Firmicutes."
10. Wolf, K. J., & Lorenz, R. G. (2012). Gut Microbiota and Obesity. Current Obesity Reports, 1(1), 1–8. http://doi.org/10.1007/s13679-011-0001-8. Link to NIH full study. 
11. Zimmer, Carl. Gut Bacteria Divide People into 3 Groups. New York Times, Apr 20, 2011. Link to article.  Link to Nature article.