Lecture 2 - Microbiomes

What is a microbiome?

Microorganisms, their genomes, and surrounding environmental conditions

What is a metagenome?

Collection of genomes and genes from members of microbiota

What is a microbiota?

Specific microbes or collection of microbes

What are 5 major functions of the microbiome?

1. Immune stimulation

2. Micronutrients

3. Digestion

4. Defense

5. Detox

What are four defenses against microbes?

1. Competitive exclusion

2. Physical barrier

3. Chemical warfare

4. Biological warfare

Why do some species depend on microbiome for digestion?

Vertebrates (ruminants) lack cellulose and need microbes to break down plant matter

What are the three main short chain fatty acids (SCFA)?

1. Acetate

2. Propionate

3. Butyrate

What is the function of SCFA?

-Provide nutrients for gut cells

-Promote balance between inflammatory and anti-inflammatory signals

What vitamins do the microbiome produce?

-Vitamin B12 (and other B vitamins)

-Vitamin K

How does the microbiome stimulate immune development and function?

-Stimulates GALT development

-Increases barrier function

-Promotes tolerogenic environment

-Increases antimicrobial peptide production

What is a xenobiotic?

Chemical substance not naturally produced or expected to be present

What is an antibiotic?

Substance that kills or disrupts bacteria growth

How can antibiotics cause disease?

Lead to long-term alterations in microbiome that can cause disease

What is a probiotic?

Live microorganisms (food or supplements)

What is a prebiotic?

Food for microbes (ex. fiber)

What are synbiotics?

Combination of pre and probiotics

What is a postbiotic?

Soluble product secreted from a live microorganism (ex. vitamins B and K)

What is a fecal microbiota transplant?

Transplantation of fecal microbiota from healthy donor to patient