Your upper respiratory tract, including your nose, is home to important groups of commensal microbes which work to protect your health. Many kinds of pathogens could easily enter your body as you breathe. However, one commensal microbe, Propionibacterium acnes stops the movement of pathogens by trapping them in a sticky biofilm. P. acnes makes a protein which stimulates the cells of Staphylococcus aureus, a known pathogen, to clump together and then produce a biofilm and doing so prevents infection. (Wollenberg et al., 2014)


Microbes live everywhere on your body but you have to sometimes search carefully to find them. Do you know that your mouth contains multiple rich habitats for microbes? In fact, the microbes that live on the surface of your teeth are totally different than the ones on the gum line, even though they are only millimeters away from each other. And, the ones on the roof of your mouth are vastly different from the ones that live on your tongue, even though your tongue comes in contact with the roof of your mouth thousands of times a day. (Segata et al., 2012)


The skin is an important barrier against invading pathogens and the microbiota which live on the skin play a vital role in this defense. As one example, one commensal microbe, Staphylococcus epidermidis, stimulates specific skin cells to move to the surface of the skin to create a physical barrier against pathogens. Since the skin constantly sloughs its cells, this protective mechanism seems to be exquisitely responsive to dynamic changes in the numbers and kinds of skin microbes, both commensal and pathogenic. (Naik et al., 2015)


The GI tract hosts the body’s largest microbiome with thousands of microbial species and trillions of cells. These microbial species communicate with and benefit the host in many ways. For example, the outer cell layer of one commensal microbe, Bacteroides fragilis, is made up of specific kinds of complex sugars, called polysaccharide A (PSA). It appears that the cells in the host gut lining recognize these PSAs and their presence induces particular immune cells to produce potent anti-inflammatory compounds. Regulation of host inflammation by the resident microbes might be needed after an infection has been fought, almost to communicate to the host that the battle has been won! (Mazmanian et al., 2008)


The vaginal microbiome is unique in that it appears to be a crucial source of microbes to the next generation. It is thought that the infant is sterile while still in the womb but that it picks up microbes during birth. In fact, the mother’s vaginal microbiome changes during her nine month gestation so that the right set of microbes is given to the infant. During birth, the infant is coated with the mother’s microbial mucus and these microbes then immediately begin to colonize the infant both inside and out. Most of these maternal microbes are Lactobacillus and Bifidobacterium spp, which, if the infant is breastfed, go on to flourish. It is amazing how we acquire our initial microbiome, which is crucial to our health and well-being. (Dominguez-Bello et al., 2010)

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