MICROBIOTA 3 Flashcards
what are the members of the gut microbiome (other than the bacterial community)?
helminths are not microscopic, we can see them with our naked eye
what are probiotics?
live microorganisms that confer a health benefit to the host when administered in adequate amounts (fermented foods, supplements)
what are some issues with probiotics?
- information still required: strains, doses, duration, frequency, timing, indications, side effects
- rare cases of infections associated with probiotics
- transferrable microbial properties (antibiotic resistance genes, virulence genes) especially in immunocompromised/suppressed people
- effectiveness of probiotic for altering a disease state is not provided
probiotic vs FMT experiment
healthy volunteers and mice
given antibiotics (ciprofloxacin and metronidazole) (7 days for humans 14 days in mice)
collected bacteria from mucosa, lumen and did a biopsy
-> decrease in bacterial diversity
3 conditions after that:
1. bi daily probiotic administration (same 11 straing cocktail to 21 volunteers)
2. collected a stool sample before they started antibiotics and did auto FMT to those people (they received their own fecal matter from before antibiotics)
3. spontaneous recovery, didn’t change anything
results are in the picture:
the composition of the probiotic pills was not representative of what a healthy adult microbial community, so it delayed microbiome reconstitution
-> probiotics have lactobacillus bacteria which infants use to digest milk, that is not for adults
mucosal bacterial content had the biggest response
characteristics of helminths
what are symptoms of helminth infections and how do they work
helminths are really good at establishing chronic long term infections
Th2 response is in place when you have long term infections
dampens immune system so that it doesn’t expulse the worm
the hygiene hypothesis
highly processed food, we are not exposed to enough microorganisms, our immune system is being altered and we respond too much to signals that we wouldn’t be responding to
–> could use helminths for autoimmune diseases
helminths and inflammatory bowel disease
when IBD: tight junctions are broken down, microorganisms can come through, pro inflammatory metabolites, low diversity
helminth infection: higher diversity, good mucosal production, decrease in inflammation
what are some body wide effects of gut helminths
this happens through the different metabolites and the dampening of the immune response
worm therapy considerations, things that we dont understand
bacteriophages characteristics
viruses that only infect bacteria
they are recognised by immune system
exist everywhere that bacteria are present
typically outnumber bacteria 10:1
self replicating obligatory parasites without inherent metabolism
high morphological diversity
several molecular tools used in the lab (DNA pol restriction enzymes and CRISPR come from phage research)
they come in all shapes and sizes
there are RNA, DNA, ss, ds phage
phage diversity
what are the replication cycles of phages
only know about the first two, just know that the last two exist
chronic and pseudolysogeny and variations of the lysogenic cycle
phages in the gut
majority is DNA
phage:bacteria ratio is lower than in other systems (between 0.1 and 3)
some phages: caudovirales and lak phage
regulated by biotic and abiotic factors
have different phages depending on where it is in the gut
most are integrated in bacterial cells (prophages)
more stable, high similarity between relatives and household members
can directly/indirectly modulate the immune response
can also be recognised by the immune system because of cap proteins that are foreign
populations of phage over lifetime
infact: mostly lytic, more viral abundance/diversity
adult: mostly prophages, more bacterial abundance/diversity
how do phages regulate bacteria
abundance: kill them
diversity: phages have restricted host ranges
phenotype: gene exchange
phage population in healthy vs inflamed gut
what is child stunting
not genetic, affected by malnutrition
also associated with increased diarrheal diseases
stunted mother is at higher risk to have stunted children
–> higher risk of developing infectious diseases, will miss important life milestones
phages and child stunting
phages can affect bacterial communities in vitro
phages from healthy children: dampened the growth of proteobacteria
this only happened in younger children (under 23 months) that had a mix of milk and solid food diet
