Lecture 8 - Microbiota

Question 1

what are commensals and how many do we have as humans

Answer 1

basically good bacteria
no harm to human health
3.8x10^13 bacteria (compared to 3x10^13 human cells)

Question 2

what is the microbiome

Answer 2

the genome of all the microorganisms in and on our body

Question 3

how big is the skin

Answer 3

2 square metres

Question 4

what are the 3 types of bact on the skin

Answer 4

resident bacteria - (skin flora - outdated name)

staphylococcus aureus (origin of MRSA)

transient bacteria (washing ur hands would get rid of these, unlike the others- viruses, poo bacteria etc)

Question 5

what type of pathogens exist in the nasal cavity

Answer 5

oppurtunistic pathogens
- MRSA
- meningitidis
- influenzae
- pneumoniae

Question 6

what’s diff about bacteria in oral cavity compared to nasal and skin

Answer 6

vry high biodiversity
lots more species

Question 7

where do bacteria bind in oral cavity

Answer 7

salivary pellicle receptors

Question 8

name the bact in stomach that causes gastric ulcers

Answer 8

Helicobacter pylori
gastritis –> cancer (vry small % of people will get this, usually its fine)

Question 9

in the GI tract, where is majority of bact

Answer 9

colon
10^10 cells per g

Question 10

what type of bact are vast majority of bact in colon

Answer 10

obligate anaerobes
some facultative aerobes, but they use up all O2 (.g. Ecoli)

Question 11

what is bacteria dependent in colon between humans

Answer 11

dependent on diet
so a vegetarian has diff bact to carniverous

Question 12

what bacteria break down oligosaccharides in breast milk

Answer 12

bifidobacter

Question 13

by what age does childs microbiota becomes liek adult microbiota

Answer 13

3

Question 14

whats the microbiota change seen in those over 60

Answer 14

increase in Firmicutes
just know that theres a shift in bacteria types (not fully understood yet)

Question 15

how does bact provide us with 10% of calories from food

Answer 15

the bact convert complex indigestible stuff into short chain fatty acids that we can absorb and use

Question 16

what does animal body provide bacteri

Answer 16

organic nutrients
growth factors
constant pH, osmotic pressure, temp.

Question 17

what bacteria causes dental cavities

Answer 17

streptococcus mutans

Question 18

what is dental plaque consisting of

Answer 18

primary and secondary colonisers
with more anaerobic bact as u go down

Question 19

why is important to separte small intestine and colon in terms of amount of bact

Answer 19

• al lot less bacteria in SI
  -So bact doesn’t compete with us for the nutrients we need.
  All the stuff we don’t need go into colon – bacteria will break them down and help us get most amount of stuff from the food

Question 20

what doe c section lead to a reduced colonisation of

Answer 20

bacteroides and bifidobacterium in gut in early developmet

Question 21

how is microbiota linked to mood

Answer 21

gut-brain axis (ehich connects CNS w/ enteric nervous system)
stress, depression, obesity, autism
all linked to microbiota

Question 22

what was ratio of bact in obese mice vs normal mice and why

Answer 22

• obese mice had more firmicutes than bacteriodetes
• so shows the firmicutes better at farming calories

Question 23

what happened when obese mice treated w/ vancomyocin

Answer 23

• kills gram + bact
• so it killed fermicutes but not bacteriodetes
• lost weight