Microbiota 1,2,3 Flashcards
define microbiota
assemblage of MOs present in a defined environment
define the human microbiota
The total microbial community that resides both on and within us.
what is the bacteria: host cell ratio?
1.3:1
does the bacteria: host cell ratio vary?
yes depending on when you’ve been to the toilet
explain the sterile womb hypothesis?
the initial host colonisation
human womb is sterile- no microbes unless there’s a complication
acquisition occurs during the birth process
vaginal microbiota and/or skin and surrounding environment is involved in the initial colonisation
is the womb sterile?
yes unless there’s complications
what’s involved in initial colonisation of children?
vaginal and/or skin microbiota from mother
surrounding environment
what is the alternative theory to sterile womb hypothesis?
in utero colonisation
what is in utero colonisation
womb isn’t sterile and is colonised by gram negative bacteria- likely to be contaminants
what evidence is there for in utero colonisation
enterobacter and escherichia DNA found in amniotic fluid
when does the microbiota reach a climax community?
3 years of age
what is development of the microbiota based on?
environment e.g. sun exposure
diet- breast milk or formula?
antibiotic exposure in infancy
TF: microbiota acts as a metabolic organ?
true
2 most important phyla in the GIT?
Fimicutes and bacterodetes
do people all have the same amounts of Fimicutes and bacterodetes
no- large sis
3 ROLES OF GUT MICROBIOTA IN HEALTH?
- induction of intestinal angiogenesis
- colonisation resistance
- metabolism of carbohydrates and proteins
what is induction of intestinal angiogenesis?
development of villus capillary network
example of a bacteria which contributes to induction of intestinal angiogenesis?
bacteroides thetaiotaomicron
explain 3 ways in which bacteria in the colon contribute to colonisation resistance
takes up the available surface meaning that any new pathogens cant attach and cause complications
also use food for energy- use up nutrients so there’s less for invading pathogens
change the pH- make organic acids which can infer growth inhibition for pathogens
explain the role of bacteria in carbohydrate and protein metabolism
simple sugars can be non digestible so need bacteria to digest
example of non-digestible carbohydrates?
cellulose, resistant starch, inulin
what type of foods make it to the later stages of the gut?
greens
where are simple carbohydrates broken down by bacteria?
in the early stages of the gut- this is where the necessary bacteria reside
examples of short chain fatty acids produced by the bacteria? what effects do these have?
butyrate
propionate
acetate
anti-inflammatory and anti-carcinogenic
summary of link between microbiota and obesity in mice?
- Gut microbiota of obese phenotype (Ob) associated with fewer Bacteroidetes phylum- balance was more in favour of finicetes. But when compared to lean phenotype (Ln) it was more 50:50
- Co-habitation of Ln and Ob mice altered metabolic profile to a lean-like state. Why?
- Mice are coprophagic- eat their own poo- so if you put them on the same diet in a mixed cage. The Ob was consuming the Ln faeces- colonising itself which altered metabolic profile to a lean like state.
- Increasing the Bacteroidetes in the diet= reduction in its food consumption. The altered gut microbiota was changing the amount of food the mouse needed.
