microbiome

Question 1

microbiome

Answer 1

totality of microorganisms and their collective genetic material present in or on the human body or in another environment

Question 2

16S ribosomal RNA

Answer 2

Prakaryotic ribosome is a 70s made of 30s and 50 s and within the 30 S is a 16 s gene

Question 3

Microbiota composition varies by body site

Answer 3

gut is home to a big part of microbiota (majority)
Gut contains the majority of the microbiota
you have 400-500 different species of bacteria in gut
genome size is 150x of humans
many different species
w/o disease each individual’s microbiota is stable over time
high interindivitual variation (people arent the same)

Question 4

what makes up the micriobiome

Answer 4

nutreints (mucus and surface carbs)

immune effectors (AMPs/defensins, IgA)

Non immune factors (Bile salts and digestive enzymes)

Luminal microenvironment (oxygen ph, ions)

Question 5

bacteriocins

Answer 5

Plasmid-encoded antimicrobial peptides:

encoded on pheromone responsive, conjugative plasmids
Target and kill bacteria of the same species
can be circular or linear
bacterial strain that makes the plasmid has an immunitiy peptide
bacteria can use the conjugation apparatus and transfer plasmids

Question 6

what differs commensals and pathogens

Answer 6

genome size is larger for commensals, commensals

Question 7

nutrient utilization and competition

Answer 7

symbiotic bacteria will digest polysaccharides that are unable to be digested by epithelial cells and the epithelial cells will eat up the carbohydrate metabolites

pathogen cant eat so it will go into the epithelium

Question 8

functions of intestinal microbiota

Answer 8

drives a balance of homeostasis, nutrients, and immune system, fermentation of stuff you cant digest, gets out nutrients

Question 9

microbiological barrier

Answer 9

the duality of the commensal microbiome
mucosal surfaces are in constant contact with microbes
which allow normal function and protect against infection
mucosal immune system protects host from microbiota

Question 10

microbiota induction of epthelial antimicrobials

Answer 10

done thru interactions with toll like receptors (PRR) recognizing PAMPS and trigger the production of antimicrobials from the epithelial cells keeping bacteria at a safe distance away from the gut lining

Baso lateral signaling thru DCs sampling and producing factors and making chmockines and cytokines

IgA thru immature b cells in lymph nodes or MALT

induction of T cell subsets Th17 cells and Treg cells

Question 11

The role of the microbiota in host metabolism

Answer 11

commensal bacteria regulate digestion by :
mediation bile acid synthesis
lipid absorption
amino acid metabolism
vitamin synthesis
Short chain fatty acids (SCFA) from bacterial fermentation

By products of bacterial fermentation metabolites regulate the immune system

bacteria is not actually touch the epithelium

Question 12

Microbiota associated metabolites that shape mucosal immunity

Answer 12

3 SCFA: Acetate(CD4), Bupturate*, and Propriotate(Treg)

*main one that helps growth

Question 13

obesity

Answer 13

decreased gut microbiome richness

Question 14

role of the microbiota in host protection colonization resistance

Answer 14

Commensal microbiota prevent pathogen colonization via:
bacteriocin production
SCFA prod
Competition of Oxygen, Nutrients, Attachment sites
Induction of epithelial antimicrobials
induction of mucus production and secretion

c diff is the bad thing

Question 15

manipulating microbiome

Answer 15

probiotics fecal transplant for c diff