Lecture 5: Human Microbiome Flashcards
endosymbiotic theory
o Billions of years ago endosymbiosis was the original form of “outsourcing”
o Even now, all multicellular organisms share their surfaces with bacteria
o We have co-evolved with our microbial friends
o We outsource tasks to them and would not be able to do all our tasks if we were suddenly “germ-free”
o For every human cell in your body, there are 10 microbial cells
o For every human gene there are 360 microbial genes
Biome
o Areas of the earth where the environmental factors are similar, such that particular groups of species can survive and thrive
o Biomes/ecosystems are made up of many different species or organisms that exist in a tangled, interconnected web
o Climate geography and symbiosis interweave
o Can’t change one thing without changing the whole thing (ripple effect)
Human Microbiome
diversity of microbial species that live in/on us
what does our microbiome influnce
- Metabolism
- Likelihood of developing diabetes
- Likelihood of developing cardiovascular issues
- Behavior (how we handle stress and anxiety)
- GI disease (likelihood of getting them)
- Allergies
- Autoimmunity
- Likelihood of developing some cancers
Our ecosystem
o Human microbiome is incredible complex
o In reality, there are 7 ecosystems
o Mostly use fecal samples to research microbiome
o Difference btw Yellowstone national park and Sahara desert=difference btw gut microbiome and skin microbiome
o Gut microbiome has over 10 trillion individual and 1000 species
99% of our microbiome
is in our gut
microbiomes similarities and differences
o All healthy adults share most of the same gut bacterial species—core microbiota
o Samples obtained from 1 individual over time—we each have a distinct stable community with some deviations
Where do we get our microbiome
o Largely established in the first 3 years of life
o Where we’ve been (how our microbiome differs from others)
• C-section vs vaginal birth
• Skin to skin contact with parents
• Home environment, pets
• Diet
From what we eat
• Diet has an immense impact on microbiome
• Consuming high-fat, low-fiber foods or low-fat, high fiber diet for 10 days is sufficient to induce significant change in microbiome
Effects that microbiomes have on us
o Disruptions in normal microbiota-host interactions are implicated in: • Obesity • Malnutrition • Inflammatory bowel disease • Neurological disorders • Cancer
Nutrient extraction
- Much of the food we ingest is actually indigestible to us
- “fiber” is actually 100s of different molecules that we can’t digest
- which molecules we feed our gut=changes in different microbe populations
- changes in diet influence gut microbe diversity
- changes can be rapid—days
Microbiome energy use and storage
- metabolites from microbes get into bloodstream and alter energy storage in liver and muscle
- all this indicates that microbes can play an active role in directing weight gain
microbiome and immune system
o Some microbiomes can induce a state of anti-inflammation and immune suppression that allow them to persist
o This may help lead to an overall anti-inflammatory state, which is linked to lower disease risk
o Healthy and diverse microbiome creates an environment of competition
o Harder for disease-causing microbes to establish infection
Microbiome and infectious disease
o Certain gut microbes can elicit antibody responses that are protective against malaria
o Composition of the skin microbiota can change the degree of attractiveness to mosquitos
Do we have to take care of our microbiome?
o Yes and no
o Our microbiome appears to undergo transient shifts, but largely returns to its set point right after
pre biotic
non digestible foods that stimulate growth of bacteria in the gut (fiber: whole grains, fruits, etc)
