Gut microflora Flashcards
what is the gut microflora role in food
role in digesting food we eat and influenced by food we eat
maximise what we get out of the food
where is the majority of the gut microflora
large intestine (compartmentalised)
does the gut microflora cause harm
is a mixed colony in host - mutual benefit
what do the gut microflora do
species produce enzymes not made by the host
two main categories:
- carbohydrate degradation
- protein degradation
carbohydrate metabolism problem
portion of ingested carbohydrate not all digested in small intestine
principally starch, cellulose, hemicellulose
what happens during carbohydrate metabolism
complementary biochemical reactions carried out by different GMFs:
polysaccharide - oligosaccharide - intermediate product
then:
- liberation of short chain fatty acids - capable of absorption by large intestine
- CO2, H2, SO4 formed
what do GMFs metabolise
GMFs metabolise the ingested carbohydrate
what do CO2, H2, SO4 produce in carbohydrate metabolism
they form CH4, H2S and acetate
acetate reused in metabolism as it is a SCFA
where do GMFs get their nitrogen source from
proteins
why is protein so important for some GMFs
they use it as their source for carbon, nitrogen and energy
what is the problem with protein metabolism using GMF
breakdown of proteins by GMF makes many compounds that are potentially toxic to host
what examples of toxins are produces
phenols
ammonia
amines
indoles
how is GMF linked to ammonia
lowers ammonia concentration - incorporate into new proteins in cell growth
how does carbohydrate metabolism affect ammonia
carbohydrate metabolism stimulates ammonia uptake by GMF
what substrate is present in dietary components
exogenous substrates
what substrate is present in compounds produced by host
endogenous substrates
what does GMF use as a nutritional source
endogenous substrate
how is GMF studied in a direct culture
isolate and grow the GMF in lab
what is the problem with studying GMF In a direct culture
not all species will be culturable
only allows relatively crude identification
what is the simplest way to study GMFs
genomics
isolate genome and study
read and define genes
what is metagenomics
study of genomes in entire community including non-culturable ones
what occurs during metagenomics
genomes reassemble
use databases to predict functions of each gene
based on similarity to existing genes of known function
what is the benefit of metagenomics
relatively cheap
what has metagenomics shown of GMF
varies a lot:
between populations
depending on diet
in same individual over time
