Gut Microbiota Flashcards

1
Q

How many organisms do we contain in our body?

A

100 trillion organisms: mostly bacteria, archaea, eukaryota, (fungi, and protozoa)

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2
Q

Where is the highest concentration of organisms in our body?

A

colon because we have a low pH in the stomach

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3
Q

Where is the most of our gut bacteria from?

A

90% from the phyla Firmicutes and Bacteroidetes, other important phyla is Actinobacteria (Bifidobacterium), and Proteobacteria

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4
Q

Are mucosa-associatd bacteria different from luminal bacteria?

A

Yes

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5
Q

Why do we refer to the colon as a microbial organ?

A

it contains 150x more genes than the human genome - includes a complex collection of glysocide hydrolases and polysaccharide lyases that break down complex carb linkages into consumable oligosaccharides or monosaccharides

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6
Q

How many % bacteria are we?

A

90

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7
Q

Proteobacteria

A

some pathogens

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8
Q

What do bacterias do?

A

digest indigestable things

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9
Q

5 functions of gut microbiota

A

enhances energy extraction through fermentation - SCFA production
essental vit synthesis
regulates immune system development
xenobiotic elimination
maintains integrity and function of gastrointestinal barrier

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10
Q

Dysbiosis

A

altered gut microbiota - could be associated with many diseases/disorders

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11
Q

Obesity and related gut microbiota - 2

A

decreased in abundance of dominant bacterial phyla -
bifidobacterium, and faecalibacterium prausnitzii
decreased microbiome diversity - high specificity and sensitivity

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12
Q

If bacteria in our digestive system went into the bloodstream

A

it would be attacked

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13
Q

are we born with gut microbiota?

A

no, GI tract of a fetus is sterile

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14
Q

Colonization of the infant gut (4)

A

genotype
mode of delivery - vaginal they get the gut bacteria of mother - lactobacillus prevotella, c-section - staphyfococcus, corynebaterium, propionibacterium, higher susceptibility to certain pathogens (skin/operating room), higher risk of atopic (hypersensitivity) diseases
early life exposure to antibiotics - kills everything
feeding practices - breast fed - increases bifidobacteria, formula fed - increase diversity

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15
Q

microbiota fingerprint established by

A

age 3 - remains stable

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16
Q

microbiota biome in early childhood - 4

A

new strains less certain in origin outcompete old ones
rapid increase in diversity
early microbiota development - high instability
shifts in response to diet and illness

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17
Q

adult microbiota biome - 2

A

highly distinct, differentiated microbiota

continue to change but at a slower rate

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18
Q

elderly microbiota biome

A

different than young adults

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19
Q

germ free vs germ mice and the amount of food

A

germ free ate more food 30%

germ ate less but had 40% in body fat

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20
Q

5 strategies to manipulate gut microbiota

A
prebiotics 
probiotics 
synbiotics 
antibiotics 
microbiota transplant
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21
Q

prebiotics - 2

effects attribute to - 4

A

non-digestible food ingredient food for healthy organisms - stimulate growth and metabolic activity - does not benefit from probiotics
- stimulation of beneficial bacteria and SCFA production
- improved barrier function
- suppression of lipogenic enzymes - decreased synthesis of lipoproteins and triglycerides
stimulation of glucagon like peptide secretion

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22
Q

probiotics - what are they, how do they do it? 2 common species

A

live health promoting organisms - benefit from prebiotics
- directly interact with host cells/indirectly through effects on other bacterial species
bifidobacteria, lactobacillus

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23
Q

synbiotics

A

combination of a synergistic prebiotic and probiotic

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24
Q

antibiotic

A

agent to inhibit growth of bacteria

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25
Q

microbiota transplant

A

transplantation of fecal bacteria

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26
Q

common prebiotics - 3

A

inulin, fructo-oligosaccharides, galacto-oligosaccharides

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27
Q

potential prebiotics - 3, what kinda diet can you go on?

A

resistant starch, xylo-oligosaccharides, arabinoxylan-oligosaccharides, high fiber/microbiota-accessible carb diet

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28
Q

6 food examples of prebiotics

A

bulb of leeks, jerusalem artichokes, jicama, onions, cooked and cooled potatoes, garlic

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29
Q

2 bacterial groups affected by prebiotics

A

generally bifidobacterium and lactobacillus

other beneficial organisms that may be increased are akkermansia mucinphila and faecalibacterium prausnitzii

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30
Q

what feeds bifidobacterium?

A

fructose molecule links that we cant break

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31
Q

where do we get resistant starch? -2

A

cooked and cool potatoes, hard bananas

32
Q

lean vs obese people microbes in germ free mice

A

obese would eat less and gain more weight

33
Q

why are processed foods bad for your biome?

A

sugars that are absorbed and go right into your blood stream and starve your microbes

34
Q

how can you tell if a food is high in fibre

A

things that get stuck in your teeth and are undigestible so lentils and leeks and bukwheat and quinoa

35
Q

current diet and dietary fibre

A

huge drop

36
Q

what nerve communicates between the digestive system and the base of the brain?

A

vagus

37
Q

10 days of fast food and your microbe biome

A

6000 to 3500

38
Q

how long did it take for the fast food guy to regain his biome diversity?

A

more than 2 weeks

39
Q

antibiotics and biome

A

wipes out everything and the species go down in number, increasing the chances that they will be fat later

40
Q

chances of being fat and c-section

A

22%

41
Q

what other daily activities can increase your biome? -2

A

playing in dirt and with pets

42
Q

bariatric surgery and biome

A

may be more than a new stomach

43
Q

more ___ of food can increase your microbe biome

A

diversity

44
Q

microbes can have widespread impact on?

A

diverse aspects of a host’s physiology

45
Q

Microbiata dysbiosis are starring in

A

growing list of western diseases such as metabolic syndrome

46
Q

dysbiotic must be accompanied by

A

the recognition that the definition of a healthy microbiota that should serve a a frame of reference

47
Q

MACs

A

microbiota accessible carbs - carbs metabolically available to gut microbes - dietary and resistant to degration and absorption by the host - may come from a variety of sources including plants

48
Q

MACs for infants

A

breast milk known as human milk oligosaccharides

49
Q

most common microbiota fuel for humans and it gives?

A

dietary plant/dietary fibre - carbs for gut microbrobe fermentation

50
Q

What can the missing mechanistic explanation for the beneficial effects of dietary fibre be?

A

fermentation by the microbiota

51
Q

Scenario for high MAC diet

A

few simple sugars, microbiota will create SCFA fermentation end products to create microbiota diversity and increase metabolic output - play diverse regulatory role including protection from many western disease

52
Q

Scenario for low MAC diet

A

loss of beneficial microbial metabolites such as SCFA and weird microbiota, lower microbiota diversity and leads to western disease

53
Q

gut microbiota of children from a rural village in Burkina Faso compared to “healthy” estern cohort in Italy - 3
what do they eat?

A
  1. altered ration of 2 dominant phyla - increased rep of bacteroidetes relative to Firmicutes
  2. increased microbiota diversity
  3. large increases of SCFA production including 4-fold more butyrate and propinoate
    twice the dietary fiber
54
Q

microbiota from traditional agrarian gps compared to western counterparts

A

more similar to one another in microbiota diversity and SCFA production

55
Q

link between microbiota diversity and health

A

unknown, but SCFA is likely a mediator - high MAC ->diversity-> fermentation end products in circulation (short chain FA, acetate, propionate, butyrate)

56
Q

SCFAs are - 3

A

acetate, propionate, butyrate - energy source for the colonocytes absorbed by host - kcals salvaged/fermented from inaccessible carbs - also diverse regulatory role

57
Q

dietary fiber and SCFA can

A

protect one from diet induced obesity

58
Q

argument supporting why the ancient microbiota is better

A

traditional societies have mushc lower rates of western diseases

59
Q

ability of microbiota to accommodate dietary change (MAC deprivation in generations of developed countries)

A

deleterious to its own maintenance and our health

60
Q

metabolic syndrome often preceds

A

onset of T2D and CV diseases

61
Q

main barrier between internal sites from luminal antigens is composed of

A

colonocytes and the seal between them provided by the tight junctions

62
Q

Microbiota enhances 2

A

gut barrier function and protects against translocation of bacterial toxins by competition with potential pathogenic bacteria for nutrients

63
Q

butyrate - 2

A

SCFA of particular interest for gut barrier function as it is a preferred nutrient for colonocytes - appears to enhance gut barrier function by regulation of TJ proteins and mucins.

64
Q

prebiotic effect of a food component

A

stimulate growth of bifidobacteria and lactobacillus

65
Q

saccharolytic

A

capable of hydrolyzing a sugar molecule - gut bacteria because humans eat carbs

66
Q

Metabolic endotoxemia - what is it? mechanism?

A

endotoxins in blood - could be caused by high fat feeding - increased translocation of gram neg bacteria and bacteria derived components such as LPS into the bloodstream

67
Q

intake of prebiotic fibres in combo with high fat diet

A

can counteract diet induced metabolic disturbances

68
Q

microbiome in metabolically healthy ind appear to be - 3

A

enriched in bacterial gene functions, metabolism of co-factors and vitamins, and production of butyrate

69
Q

using qPCR (real time polymerase chain reaction) to characterize the gut microbiota

A

identified increased abundance of bifidobacteria species in healthy vs obese and T2D

70
Q

interventions with diff types of dietary fibre including prebiotics has shown to - 3

A

modulate gut microbiota and improve insulin sensitivity, low-grade chronic inflammation, and lipid metabolism

71
Q

prebiotics create?

what does it help with?

A
SCFA 
- acetate 
- butyrane 
- propiate 
decrease pH
72
Q

6 mechanisms of prebiotics

A
gut microbiota 
- increased bifidobacterium, lactobacillus 
- increase SCFA and decreases pH 
improbed gut barrier 
- increased GLP 2 
Reduced inflammation 
- decreased LPS 
Reduced adiposity 
- decrease lipogenesis 
increased satiety 
- increased GLP1/PYY 
-decreased Ghrelin/energy dilution 
Improved glycemia 
- increased GLP 1 and decreased visceral adipose tissue
73
Q

How specific are the beneficial effects of probiotics?

A

strain specific

74
Q

5 probiotic mechanisms

A
gut microbiota 
- increase strain of probiotic organism 
- exclusion of pathogenic organisms 
- reduced inflammation through probiotic interaction with immune cells 
Improved gut barrier function 
Reduced inflammation 
- decreased LPS 
Reduced adiposity 
- decreased lipid uptake 
improved blood lipids 
- increased bile acid secretion 
- decrease lipid uptake
75
Q

extinct organisms in the gut

A

need to be reintroduced

76
Q

PA and gut microbiota

A

increases diversity

77
Q

Non-caloric artificial sweeteners and gut microbiota

A

increase insulin resistance