Lecture 4 - Human Microbiota

Question 1

Which locations in the body have the most diverse microbiota? Which are sterile?

Answer 1

Most microbiota: oral cavity, large intestine and rectum, skin

Sterile: Blood, bladder , uterus, CNS

Question 2

What are the two major phyla of bacteria in the gut?

Answer 2

Firmicutes, bacterioides.

Question 3

Name five functions of the gut microbiota.

Answer 3

1. Produce products for the host like vitamin K
2. Help with digestion
3. Induce immune development (IgA)
4. Maintain barrier integrity of the gut epithelium
5. Protection from pathogens

Question 4

Name three possible causes for dysbiosis of gut microbiota.

Answer 4

1. Ideal bacteria never introduced early on (e.g. c-section)
2. Modern diet not supportive of our coevolved microbiome
3. Commensal bacteria reduced or lost entirely from the gut (e.g. antibiotic treatment)

Question 5

How quickly can gut microbiota composition change as a result of diet?

Answer 5

Almost instantly!

Question 6

What happened to the mouse that got the obese twin’s microbiota transplant?

Answer 6

It got fat until it ate the lean mouse’s turds, then it got lean. Then they gave both mice western food, and the one mouse got fat again, despite continuing to eat the lean mouse’s poop.

Question 7

Can microbiota transplants be used to treat C. difficile infection?

Answer 7

Yes and it was successful.