Gut Microbiome Flashcards
gut microbiota
a symbiotic ecosystem of living organisms (viruses, archaea, bacteria, fungi) that inhabits the lumen of the human digestive tract from birth
probiotics (definition)
purified strains of gut bacterial species ingested for a pharmacologic effect
prebiotics (definition)
*compounds (often components of food) administered to feed the microbiota
gut microbiome - symbiotic mutualism
*benefits for the microbes: anaerobic environment (low pO2), warm, wet, dark, stable pH, electrolytes, nutrients, vitamins
*benefits for the human host: unabsorbed nutrient reclamation, bioactive metabolic products, protection from pathogenic organisms
origin of the gut microbiome
acquired at birth from mother and thereafter from the environment
population distribution of the gut microbiome
*proximal to distal density gradient (least in stomach, most in colon)
*proximal suppressive factors: gastric acid, bile acids, secretory IgA, gut motility
factors influencing the gut microbiome
*diet
*lifecycle (breastfeeding, aging, etc)
*luminal factors (gastric acid, bile acids, etc)
*host genetics
*drugs (antibiotics, PPIs, etc)
*bowel disease (IBD, surgery, etc)
genetic methods used to characterize the bacteria in the gut microbiome
*16S ribosomal RNA gene sequencing [the gene for the bacterial ribosome 16S subunit contains highly conserved regions (allows universal PCR targeting) AND hypervariable regions unique to each bacterial species (like a fingerprint)]
*sequencing technology has become highly automated
impact of dysbiosis (loss of diversity in gut microbiome) on health
dysbiosis has been implicated in:
-obesity
-fatty liver disease
-diabetes & glucose intolerance
-inflammatory bowel disease
-cardiovascular disease & stroke
-neoplasia & cancer progression
BUT it remains to be proven whether the dysbiosis is a primary cause or an associated effect of these disorders
