MICROBIOTA 1 Flashcards
what are humans made of?
eukaryotes+bacteria+ archaebacteria + viruses (bacteriophages)+parasites
what is the difference between microbiota and microbiome?
microbiota: cells
microbiome: genes
what is the relationship between microorganisms and humans
can fall anywhere on the symbiosis spectrum: mutualism, parasitism or commensalism
what is the holobiome
human genome + microbiome
why should we care about the microbiome?
how is the microbiome traditionally studied?
what are some culture independent methods of studying the microbiome?
how is 16S rRNA studied?
what is metagenomics
how do microbial communities distribute?
site specific in the body, they cluster by body site
skin: actinobacteria
vagina: lactobacillus
gut: bacteroidetes and firmicutes
mouth: streptococcus
which bacteria are on the skin and what do they do?
composition affects attractiveness to mosquitoes
which bacteria are in the oral cavity and the nose?
which bacteria are in the urogenital tract
protects against yeast and fungal infections
also varies with sexual activity
which bacteria are in the penis microbiome?
which bacteria are in the GI tract?
70% of the total microbiome is in the colon
the bacteria vary based on the oxygen levels
what is a proxy to analyse the gut microbiome?
fecal samples
how do we acquire a microbiome?
feotuses used to be considered sterile
if there is microbes found in the placenta, that is not a good sign
large amounts of microbes are acquired at birth and colonization varies with delivery mode (vaginal or c section)
vaginal delivery: baby gets more vaginal bacteria
c section delivery: baby gets more skin bacteria
how does the microbiome change over time
defined succession: establishment of facultative anaerobes (enterobacteriaceae) and bifidobacteria first
after six months, its mostly obligate anaerobes
at 3 years you have adult like microbiota
bacteria phyla remain stable over the course of months but species and strains are much more variable
how do you get data that is stronger than correlation?
in vitro studies
animal studies
human studies
each model has limitations
changes in tools technologies and analytical pipelines
how are mouse models used to study the microbiota?
how are axenic and gnotobiotic mice maintained?
what are differences between humans and mice?
mice are coprophagic: they eat each other’s poop
but that means you know that all the mice in the same cage share the same bacteria
only about 30% of bacterial species are shared between mice and humans
but mice models can provide us with means to determine causality and mechanisms of interaction
what are holobionths
unit of biological organization composed of a host and its microbiota
