Microbiome

Question 1

Protective fxns of GI microbiota

Answer 1

1. Pathogen exclusive
2. Nutrient, receptor competition
3. Antimicrobials: lactic acid, H2O2, pH, bacteriocins

Question 2

Structural fxns of GI microbiota

Answer 2

1. Barrier Fortification
   - membranes will be a bit more leaky without commensals
2. Immune system development (IgA induction)
3. Tight jxns (and other developmental cues)

Question 3

Metabolic fxns of GI microbiota

Answer 3

1. Ferment non-digestible polysaccharides and mucus
2. Synthesize vitamins: B, K, Biotin, Folate
3. Sequester metals

Question 4

Microbial contributions to GI metabolism

Answer 4

1. Microbial fermentations supply 10% of our calories

2. They supply E sources:
(can break down undigestible polysaccharides to:
1. Propionate
2. Butyrate
3. anti-inflammatory mediators)

Question 5

How do microbes contribute to obesity?

Answer 5

Bacteria themselves can contribute to obesity

Microbiome changes/inherited and drives weight gain + greater adiposity

Question 6

Commensal immune fxn

Answer 6

Every fxn from innate to adaptive immunity are fewer in germ free mice, so gut bacteria can do everything
- tells immune system how to develop appropriately

Question 7

Microbiome increases exponentially at birth. Which organism peaks at 7 days, and which at 6 mo (weaning)?

Answer 7

7 days: proteobacteria (E. coli)

6 mo: Actinobacteria (bifidobacteria)

*chart is good

Question 8

Which bacteria predominates in stool?

Vagina?

Answer 8

Bacteroides

Lactobacilli

Question 9

Dysbiosis

Answer 9

Imbalance in commensal microbiota

- can cause disease, or be caused by it

Question 10

Hallmark of pathologic exclusion

Answer 10

C. diff

other bacteria inhibit the blooming of pathogenic bacteria

Question 11

Feco-microbiome transfer

• methods
• cons?

Answer 11

Via gastroduodenal tubing or enemas

Can help against C,. diff

COns: weight gain
- overweight –> underweight

Question 12

Vaginal delivery ca introduce babies to what bacteria vs c section?

Answer 12

Vaginal:
- Bacteroides, E. coli

C section:

• enterobacteria
• Clostridia

Question 13

How can gut flora contribute to CVD?

Answer 13

Hu eat carnitine/choline (meat) –>
Gut flora metabolizes it to trimethylamine (TMA) –>
TMA is toxic and usually goes to liver and gets oxidized to TMAO

*believed that TMA causes macrophage dysfxn

Question 14

How does the microbiome contribute to liver disease?

Answer 14

Dysbiosis coupled with Western diet promotes Fatty Liver disease ad steatohepatitis

Bacteria:

1. Synth SCFA
2. Inflammation due to immune rxn to bacteria cell wall products (Edotoxemia)
3. Synth TMA

Question 15

Breast milk vs formula

- introduces infants to which bacteria?

Answer 15

Breast milk:
- bifidobacteria, lactobacilli

Formula:

• C. diff
• Bacteroides
• Enterobacteria