The Human Microbiome Christine Rodriguez, Ph.D. Harvard Outreach 2012 Summer 2012 Workshop in Biology and Multimedia for High School Teachers Microbes are all over us http://www.outreach.mcb.harvard.edu/Microbiome/download/Microbiome.pptx 11/4/16, 8=29 AM Page 1 of 22
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The Human Microbiome - Scientific Spectator care spectator/skin... · Fusobacterium sp. bacteria is a larger ... There is a normal balance of microbes on the skin that protect introduced
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The Human MicrobiomeChristine Rodriguez, Ph.D.
Harvard Outreach 2012
Summer 2012 Workshop in Biology andMultimedia for High School Teachers
Microbes are all over ushttp://www.outreach.mcb.harvard.edu/Microbiome/download/Microbiome.pptx 11/4/16, 8=29 AM
Page 1 of 22
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Thousands of different species on the skin aloneSome thrive on dry patches of the elbow, othersthrive in moist environment of armpit
There are millions of microbes persquare inch on your body
It is estimated that there are more microbes inyour intestine than there are human cells in yourbody!
What is the Human Microbiome?
Microbe: tiny living organism, such as bacterium,
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Summer 2012 Workshop in Biology andMultimedia for High School Teachers
fungus, protozoan, or virus
Microbiome: collectively all the microbes in thehuman body; a community of microbes
Biofilm: a community of microbes that livetogether on a surface
Microbes in the Human Microbiome include speciesfrom each major domain
“Extremophile”Archaebacteria
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There is a delicate balance of microbes that are maintained to keep that environment healthy.Weakened immune systems can throw off that balance and allow the wrong microbes togrow out of control.
Staphylococcus epidermidis bacteria forms a biofilm thatcoats the mucosal lining
Staphylococcus aureus bacteria is fine when kept undercontrol by a protease found in S. epidermidis, but if left togrow out of control, S. aureus can become pathogenic andcause infection
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Nose
Aspergillus fungal spores are often inhaled
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temperature, immunesystem prevent manyspecies from surviving
Oral antibioticsinhibit growth
Symbiosis of the oral microbes that are able to survive these conditions form an elaboratescaffold that lives on the tooth enamel and at the interface with the gums. It forms a barrierfor incoming bacteria.
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Oral CavityThe oral cavity has a wide variety of microbes normally found there. Here’s a few:
Streptococcus mitisbacteria typically forms a
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Fusobacterium sp.bacteria is a largerbacteria that helpsform a scaffold formany other bacteriain the oral biofilm
biofilm on the hardenamel surfaces of theteeth. If gums getinflamed, it can enter thebloodstream and causeinfection
Oral Cavity
Prevotella sp. bacteria have natural antibiotic resistancegenes. They can attach to epithelial cells or other bacteriaand cause larger infections in inflamed areas.
Candida albicans fungus can cause oral infection known asthrush
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There are several skinenvironments: oily, dry,moist. Some microbesprefer one over another.
The skin has naturaldefenses includingslightly acidic sweat andantimicrobial peptides.
Microbes hide in crevicesto recolonize skin afterwashing with soap
Antibiotic washes andoral antibiotics disturbnormal balance ofmicrobes on the skin
There is a normal balance of microbes on the skin that protect introduced microbes fromharming us. Damaged skin gives opportunities for microbes to invade the bloodstream andcause serious illness.
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• Propionibacterium acnes bacteria colonizes healthy pores, but if poresbecome clogged, it grows out of control
• Staphylococcus epidermidis bacteria normally colonizes on the skin. But whenP. acnes clogs pores, S. epidermidis also grows out of control in the infectedpores
• Staphylococcus aureus bacteria can also infect clogged pores like Staphepidermidis. Even worse, many antibiotic resistant strains of Staph aureusmake it difficult to treat the infection.
Skin
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Major barriers for microbes entering the gut:• low pH• Saliva and Bile• Immune system
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• Finding a place to attach to intestinal wall• Surviving a widely varied diet
For those microbes that manage to colonize the gut:• gut flora perform regular tasks of digestion, vitamin production, many others• Gene transfer between the myriad of species in the gut can generate new
combinations of drug resistant “superbugs”
GutBacteroides thetaiotaomicronbacteria ferments simplecarbohydrates in the gut,releasing hydrogen and CO2.
+ carbohydrates
CO2 and H2
Methanobrevibacter smithiiCH4 Methane
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archeabacteria consumes hydrogengas from Bacteroides andproduces methane, which is lostfrom gut as “gas”
Gas
Gut
Ruminococcus sp. bacteria can be found in significantlyhigh numbers in the gut flora. They break down cellulosein the gut, helping with digestion.
Helicobacter pylori bacteria has a helical shape and colonizes thestomach and upper G.I. tract. It is known to be a major cause ofstomach ulcers, although many with H. pylori do not get ulcers.
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