micro 4 Flashcards
how do microbial communities vary?
vary by site on the body
- environmental conditions and nutrient availability
where is there a high and a low bacterial density in the GI tract?
high= colon (large intestine) low= small intestine and stomach
what is the ph in the small intestine, stomach and colon?
small intestine- 6.5-7.5
stomach-1-2
colon 5-7
what is the aerobica conditions like in the small intestines, stomach and colon?
small intestine= dec oxygen content
stomach= oxygen present
solon= anaerobic
what part of the GI tract has the largest and the smallest bacterial density?
smallest= stomach -10^1-3
largest=colon 10^10-13
what is the bacterial diversity like in the small intestine?
- Low bacterial diversity
- Facultative anaerobes
- Streptococcus, Lactobacillus, Enterobacteriaceae
what is the bacterial diversity like in the stomach?
- Relatively low bacterial diversity
* Mainly Streptococcus and Lactobacillus
what is the bacterial diversity like in the colon?
- High bacterial diversity
- Particularly anaerobes
- Clostridia
- Bacteriodes
- Bifidobacterium
why do we need a gut microbiome?
when healthy a balance between good and bad microorganisms is maintained which help protect against infectious deiseaes
- they also contribute to metabolism
how does a good microbiome contribute to metabolism?
provides certain nutrients which humans cannot provide normally
- •Breakdown of non-digestible substrates (e.g. dietary fibre and intestinal mucus)•Production of short chain fatty acids (e.gacetate, propionate and butyrate)
•Amino acid metabolism (e.g. Tryptophan)
•Vitamin production (e.gB10; para-aminobenzoic acid)
is the GI of a foetus sterile?
it was assumed so- but there is data to suggest that it maternal microbes can eneter fetus GI tract- seen in first meconium (poo)
what is GI tract microbiota and gestational age related to?
associated with gut microbiota abundance and diversity
how is type of birth linked to difference in initial microbiome?
- vaginal birth derived from vaginal microbiome
- caesarean section derived from maternal skin(e.g. Staphylococcus, Propionibacterium)
what is the core microbiome for gestation/ parturation, infancy, puberty, adulthood, old age?
1- facultative anaerobes, proteobacteria 2-bacteroides, bifidobacterial 3- firmicutes, Bacteroides 4-bacteroides, firmicutes 5- obligate and facultative anaerobes
what are probiotics?
they are a chemical substrate that is selectively used by a host microorganism to produce a healthy benefit
what criterial do prebiotics have to meet?
- Non digestible and resistant to breakdown by stomach acid and human enzymes
- Selectively fermented by intestinal microorganisms
- Selectively target and stimulate growth/activity of beneficial bacteria
what are bacterial targets for prebiotic substrates?
Bifidobacteria and Lactobacilli
are all prebiotics fibre?
yes but not all fibre is prebiotic
what are probiotics?
re live cultures of miroorganisms promoted with health benefits claims;
what are 2 examples of probiotic microbacteria?
•Lactobacilli and bifidobacteria
how do probiotics work?
a- co-aggregation b-biocirfactant production c- bacteiocin and H2O2 production d-signalling effects e-competitive exclusion f-immunomodulation g-modulation of tight junctions
do probiotics work?
high quality evidence but not scientificially proven- states that they are not intended
to diagnose, treat, cure, or prevent any disease.
how is gut microflora disrupted by antibiotics?
•Susceptible cells killed indiscriminately
what can misuse of antibiotics lead to in gut microflora?
- Growth of resistant subpopulation
- Removal of repressing microorganisms
- Lead to secondary infections
