Human Microbiome Flashcards
Humans as a superorganism
-some archaea and eukaryotic species but dominated by bacteria
-high number of phaes are also present
-100 bacterial genes for every human gene
human microbiota
-collection of microbes living on/in us
human microbiome
-microbiota and environment they live in
dysbiosis
-altered microbiota that is unhealthy for the host
-typically though of as being out of balance
-loss of important commensals
-increased microbes associated with diseease
things weved learned about the microbiota
-composition and how it changes over time
-factors that influence composition
-links between microbiota composition and health and disease
some things weve learned very little about the microbiota
-community dynamics and how microbes interact
-links between microbiota as causual or correlative and the mechanism
-effiicient ways to restore healthy microbiome to an individual with dysbiosis
similarities between microbiota of different people
-similarities at the phylum level
differences between microbiota of different people
-differences at species level
is microbitoa more environmental or genetically affected
-environment
-there is a genetic component
resilience of microbiota
-changes with different conditions but generally returns to original composition
-loss of resilience can lead to dysbiosis
-resilience makes interventiosn challenging as it is difficult to displace existing microbiota
where are microbes in and on our bodies
-GI tract
-skin
-oral cavity/upper respiratory tract
-urogeneital tract
do microbes differ by location
-yes
-communities also vary signifcantly within these areas
GI tract microbiota
-low pH of stomach keeps numbers low but a microbial community does exist here
-increasing numbers as you progress-LI has very dense anaerobic population
-through GI tract pH, oxygen content and nutrients avaliablility varies (so does the composition of the microbiotia)
protection of the gastrointestinal tract
-epithelium that lines intestine protected by mucus layer
mucin
-gel like glycoprotein that serves a barrier function
microbes contact with host cells
-most microbes remain in the lumen and dont directly contact host cells
-there are interactions but there is a barrier to prevent routine, direct physical interactions with epithelium
variation of gut microbiota
-lots of person-person variation in the gut microbiota
-abundance of different genera varies by orders of magnitude
-even the most abundant genera are absent from some people
-complexity and variability make it difficult to constitue a healthy microbiota
Major phyla in the microbiota
-bacteroidetes
-firmicutes
-proteobacteria
-bacteriodetes and firmicutes dominate
bacteroidetes
-gram negative
-masters of complex carbohydrate metabolism
firmicutes
-very diverse phylum of gram positive bacteria
proteobacteria
-generally facultative anaerobes
-rapidly consume any oxygen present
-important for maintaining anaerobic environment
-high proportions of canbe a sign of dysbiosis
metabolism of the gut
-tiny bit of aerobic respiration by proteobacteria
-some anaerobic respiration
-lots of fermentations
-baceteriodetes are the primary fermenters that ferments carbohydrates from food or mucin
-SCFA absorbed by host
-many fermentation products deed diverse other organisms
four reasons the gut microbiota is very important for human health
-compete with potential pathogens “colonization resistance”
-digest food for us
-produce nutrients that we cant make that get absorbed in the colon
-promote healthy immune system, train out immune sustem and promote immune tolerance
gut microbiome links to disease
-undeniably very important for human health
-causual relationship: helicobacter pylori in stomach appears to be cause of stomach ulcers
-disruptions to microbiota early in life that reduce microbiota diversity lunked to asthma and allergies
oral cavity microbiota
-lots of aerobic and anaerobic
-growth as biofilms especially on teeth as dental plaque
-biofilms have highly organized and complex community compoisiton
skin microbiome
-varies by location of body
-some common members of microbiota are opportunistic pathogens such as s.aureus
-cuts adn wounds lead to staph infection
-produce a number of virulence factors
vaginal microbiota
-dominated by lactobacillus
-lactobacillu benefit host by lowering vaginal pH via fermentation products liek lactic acid that help prevent infection
-yeast are healthy but can rise to levels that disrupt the biome
probiotic
-live microorganisms that when administeres have a beneficial affect on host
-consuming good bacteria
prebiotic
-a substance that when consumed promotes growth of beneficial microbes
-can be simple and effective
fecal transplant
-fecal matter from healthy fonor transplantd into a patient
-attempting to reintroduce a normal/healthy microbiota into a patient experience dysbiosis
-C.diff treatment
