THE HUMAN MICROBIOME: Background
The human microbiome includes all bacteria, fungi, and microorganisms on the body. This page details what kind of organisms are on each of the floras of the body. If you would like to learn more about different types of microbes, visit the page about different microbes.
Use the table of contents to navigate this page:
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Vaginal Flora
Interactive Map
Click on the different words on the picture to get a better understanding of the different types of bacteria on the body and about each part of the body! P30.
Skin Flora
The skin flora incluces all of the microorganisms on the skin of the body. A majority of the microbes are non-pathogenic. Some of the microbes are mutualistic and others are commensal. They generally reside in the upper parts of the skin (epidermis) and in sweat glands and hair folecules. Generally, areas of the skin that are sebaceous (fatty or oily) are more dense with bacteria and fungus. The other parts of the skin include wet and dry. The bacteria, fungus and other organisms on the body is what causes body odor. The sweat itself is odor-free [21]
The diagram below shows where the microbes on the skin live (click to magnify):
"Microorganisms (viruses, bacteria and fungi) and mites cover the surface of the skin and reside deep in the hair and glands. On the skin surface, rod and round bacteria — such as Proteobacteria and Staphylococcus spp., respectively — form communities that are deeply intertwined among themselves and other microorganisms... Skin appendages include hair follicles, sebaceous glands and sweat glands."
Below are the main strains of bacteria of the skin [21]:
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Actinobacteria (51.8%)
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Firmicutes (24.4%)
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Proteobacteria (16.5%)
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Bacteroidetes (6.3%)
The diagram below lays out the different orgnaisms on skin:
Gut Flora
The gut flora includes the microorganisms in parts of the GI tract (stomach, intestines). [22] The different bacteria has been found to assist in digestion, metabolic activities, and can ethier protect from diseases or inhibit them.
Right now, there are 3 known types of gut microbiota. They have not been linked to gender, age or ethnicity but they might explain certain charicteristics about a person (obesity, metabolism etc.). [24]
Bacteroides Gut:
Prevotella Gut:
Ruminococcus Gut:
This type of gut microbiota has a higher concentration of the Bacteroides bacteria than any other.
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Known for breaking down carbohydrates
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Possible link to obesity
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Causes infections in areas not including the gut
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More common in people who eat meat and unsaturated fat [25]
This type of gut microbiota has a higher concentration of the Ruminococcus bacteria than any other.
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Known for helping cells absorb sugar
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Possible contribution to weight gain
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More common in people who consume alcohol and polyunsaturated fats [25]
This type of gut microbiota has a higher concentration of the Prevotella bacteria than any other.
The following diagram shows the variability of each enterotype (click to magnify):
The far left (enterotype 1) has a high concentration of Bacteroides and a smaller amount of type 2 or 3 bacteria. The middle (enterotype 2) has a varied concentration of Prevotella and a very small amount of type 2 and 3. The far right (enterotype 3) has more Ruminococcus bacteria than the other types.
Links to Human Health
Diabetes:
Type 2 Diabetes
When doing tests on mice, it was found that simply feeding them until they were obese did not lead to type 2 dibetes. The enviornment that they were raised in had more to do with it. The following are the findings: [27]
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Mice living in more sterile inviornments had an increased risk of type 2 diabetes
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This means that the ones in less sterile enviornments must have been exposed to certain bacteria that protected against it.
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Another idea has to do with some of the harmful byproducts that harmful bacteria make. For example, endotoxins, which generally stay in the gut, sometimes leaks into the bloodstream through the intesine walls causing inflammation and a sick reaction. Here were the findings: [27]
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The characteristics of obese/type 2 diabetes people and what happens when somebody gets sick from excess endotoxins in the bloodstream is similar
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People with type 2 diabetes have approximatley 2-3 times more endotoxins in their blood than a healthy person
Type 1 Diabetes
Research found that Finland had 7 times more cases of type one diabetes than their neighbor Russia. After further investigating, the results were as follows: [27]
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Russians are generally exposed to more bacteria through childhood (infections, fermented food etc.)
Inflamatory Bowel Disease
Crohn's Disease
When taking samples of children with chron's disease, researchers found that there was a lack of diversity in the patients with the disease. The following are the results: [28]
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In affected patients, there was a decrease in non-inflammatory bacteria such as such as Erysipelotrichales, Bacteroidales, and Clostridiales and an increase of inflammatory bacteria.
The following image explains how introduced bacteria can cause inflammation (click to magnify):
"Genetics, gut microbiota, and an uncontrolled immune response cause defects in epithelial barrier function by affecting the barrier integrity, increasing tissue destruction and mucosal inflammation."
Vaginal Flora
The vaginal flora has over 50 species of bacteria. The most abundant bacteria in the vagina is Lactobacillus. This bacteria is a major contributor in creating bacteriocins, hydrogen peroxide, and lactic acid which lowers the ph of the area. Because the ph is lower, the enviornment of the vagina is hostile and not survivable for some pathogenic bacteria. [29]
When Lactobacillus is decreased and the ph gets higher, women might experience vaginitis/vaginosis. Vaginosis is a broad spectrum of bacterial infections. This can be avoided or treated with a variety of probiotics and antibiotics. [29]
The diagram below is shows vagina's different microbes in different circumstancess (click to magnigy):
