Microbiota (what I think is important)

Question 1

When does colonization of microoganisms occur?

Answer 1

during birth

Question 2

Why can the microbiome be viewed as an organ?

Answer 2

Develop during birth, and undergoes maturation and aging like other organs

Question 3

What does dysbiosis mean?

Answer 3

“abnormal” microbiota

Question 4

Composition of microorganism?

Answer 4

1 % - viruses, archaeons, eukaryotes

99% - bacteria

Question 5

How does diet affect composition of miccroorganism?

Answer 5

Less diverse microorganism with processed food

Question 6

Describe the microflora distribution

Answer 6

• no microflora in stomach (reason why people doubted H. Pylori existed)
• majority of microflora are located in the colon (most of these bacteria in the colon are anaerobes because there is little oxygen in colon - most O2 was already reabsorbed)
• the mouth is the location with the second most amount of microflora (all the microflora are aerobes and facultative anaerobes - utilize oxygen)

Question 7

What is commensalism?

Answer 7

microbes benefit from the ineraction, but the human hoests are not affected either positively or negatively (based on traditional understanding of colonic microbes)

Question 8

What are metagenomics?

Answer 8

Metagenomics is the study of genetic material recovered directly from environmental samples.

Question 9

What are gnotobiotic animals?

Answer 9

A gnotobiotic animal is an animal in which only certain known strains of bacteria and other microorganisms are present. Technically, the term also includes germ-free animals, as the status of their microbial communities is also known.

** How is this possible? Gnotobiotic animals are born in aseptic conditions, which may include removal from the mother by Caesarean section and immediate transfer of the newborn to an isolator where all incoming air, food and water is sterilized. **

Question 10

Benefits for microbes to live in gut?

Answer 10

(1) supply of food (indigestible food, shed epithelial cells)
(2) stable, protected environment

Question 11

Benefits to humans to having microbes living in gut (there are many but he mentioned 4 new examples - specific to the layers of the gut)

Answer 11

(1) Thickening muscle wall
(2) Stimulating gut-associated lymphatic tissue (GALT) proliferation
(3) Stimulating epithelial cell generation and turnover
(4) Increasing lamina propria cellularity (may enhance functional coordination)

Question 12

Why doesn’t size matter for bacteria?

Answer 12

Despite having a smaller genome compared to homo sapiens, they have a greater number of enzymes and have enzymes that are not present in humans (ex. enzymes that digest otherwise indigestible polysaccharides - supplies short chain fatty acids for reabsorption by the host)

Question 13

How do bacteria increase the efficiency of nutrition reabsorption?

Answer 13

(1) break down indigestible polysaccharides into bacteria-derived short chain FA
(2) digest and recycle shed intestinal cells
(3) supplying essential amino acids
(4) supplying vitamins (K, B12, biotin, folic acid, and pantothenate)
(5) aiding in bile acid recycling in the colon (converting bile salts to bile acids)
(6) altering the intrinsic metabolic machinery of host cells, resulting in more efficient nutrient uptake and utilization

Question 14

What disease can dysbiosis be linked to?

Answer 14

(1) Type II diabetes
(2) Obesity
(3) Metabolic syndrome - such as a knock of Toll like receptor 5 which is essential for innate immunity
(4) Malnutrition
(5) Type 1 diabetes populations in humans

Question 15

What are the consequences of dysbiosis in type II diabetes patients?

Answer 15

• decrease in butyrate-producing bacteria
• increase in opportunistic pathogens
• restoration of microbita profile after gastric bypass surgery

Question 16

Connection between obesity and microorganisms

Answer 16

Obese-prone mice stay lean when microbiota is removed, but become obese once again after reintroduction of microbiota
( shows that obesity - a metabolic syndrome - is regulated by host-microbiota interaction)

Question 17

Connection between toll like receptor 5 and microbiota

Answer 17

• Transfer of microbiota of TLR5-null mice to germ-free wild type confers features of metabolic syndrome
• Antibiotics treatment reverses metabolic syndrmoe in TLR5-null mice

Question 18

Connection between gut microbiota and malnurition/kwashiorkor

Answer 18

-Significant difference in microbiota composition between healthy cotwins
and kwashiorkor (severe malnutrition) co-twins in Malawi
- Microbiota in kwashiorkor co-twins do not mature as microbiota in healthy cotwins.
(Main idea: Dysbiosis can cause malnutrition and malnutrition can cause dysbiosis)

Question 19

How does gut microbiota contribute to immunity?

Answer 19

(1) competition (for nutrients and adhesion sites)
(2) secrete antimicrbial factors
(3) degrade toxins
(4) stimulate immune factions

Question 20

What is antibiotics-induced dysbiosis?

Answer 20

antibiotics introduced to fight off an infection which simultaneously kills helpful microorganisms

Question 21

Why give antibiotics for viral infections?

Answer 21

Kill bacteria because bacteria in the gut can act as pathogens’ helper which means they worsen viral infections

Question 22

What is mechanic cleaning?

Answer 22

The fact that the gut secretes and moves in itself serves as protection. Mice treated with opium, an inhibitor of motility and secretion require 1000x lower salmonella bacteria to develop bacteremia (more susceptible to disease)