Unit 18 - Microbial Human Symbioses

The human microbiome contains how many microbes?

10¹³ — 10¹⁴

What is microbiota?

The collection of microbes at a particular site

What is the significance of the human microbiome?

Understanding microbiome enables diagnostics and therapeutics to improve health

The stomach has a pH of what that allows what processes?

pH = 2

Digestion of macromolecules

The small intestine has a pH of what and this allows what?

pH = 4-5

Absorption of monosaccharides, amino acids, fatty acids, water

The large intestine has a pH of what and allows what to happen?

pH = 7

Absorption of bile acids, vitamin B₁₂

Microbiota important for host health include what big 3?

GI tract, mouth, skin

What diet is around when Actinobacteria is most present?

Breast milk

Bifidobacterium longum (infantis) is what 3 things

• Gram-positive anaerobe

• Glycosidases & Oligosaccharide transporters

• Maturation of gut microbiota due to weaning

C-Section delivery has convergence with vaginal delivery?

True

What is a sign of a healthy microbiota?

Stability and resilience

What is dysbiosis?

Disruptions to microbiota structure/function

What are Short-Chain Fatty Acids (SCFAs)

Products of microbial fermentation

What does IBD do?

Lowers SCFA levels

Effects of IBD (lower SFCA levels) (3)

• Loosening tight junctions

• Increased inflammation

• Crohn’s disease and ulcerative colitis

Obesity is defined as a BMI over what?

30

What is the effect of a fecal transplant?

A microbiota transplant from obese humans to mice has caused obesity in mice and a transplant from a healthy individual to a mouse caused a healthy mouse

What do antibiotics do? (2)

• Eliminates pathogens

• Eliminates gut microbes

What two things can happen if you take antibiotics?

• Predispose to IBD/Obesity

• Opportunistic pathogens

How effective is a fecal transplant?

~90%