microbes Flashcards
microbiota
the micro organisms present in a specific site
bacteria, archaea, viruses, fungi, parasites
microbiome
microbial community that occupies a well defined habitat, including collective genome contained within the microbiota
prebiotic
a substrate that is selectively utilised by host microorganisms conferring a health benefit
probiotic
live microorganisms that, when administered in adequate amounts, confer a health benefit to the host
factors influencing microbial community composition
- environmental parameters eg.O2 tension, pH, temperature, energy sources, toxins
- interaction between microbes eg. cross feeding
- rapid evolution and speciation (which may change species)
- stochastic (unpredictable) forces eg. dispersal, dormancy
positive collaboration between microbes
cross-feeding
negative collaboration between microbes
eg. bacteria produce antibiotics (bacteriocins) that inhibits the growth of competing bacteria
dispersal
the way bacteria spread in communities eg. water spread, faecal oral etc.
intestinal microbiota and food intake
most complex polysaccharides are not digestible by the human gut, so they enter the colon and form a food source for the bacteria
bacteria (bifidobacterium and bactericides) have a diverse ability to break down different substrates and form secondary products
predictable changes in bacterial community composition with age
bacterial succession
dysbiosis
an imbalance in a microbial community associated with disease
blood of pathobionts
overgrowth of ambers of the commensal microbiota e.g enterobacteriaceae in inflammatory bowel disease
loss of commensals e. in antibiotic therapy
often accompanies by pathogen/pathobiont overgrowth eg. clostridiodes deficile associated with colitis
- replenishment may be effective in restoring balance
loss of divercity
low bacterial diversity has been documented in associstion with inflammatory bowel disease, HIV and type 1 diabetes mellitus
methods of measuring microbial communities
DNA, RNA, protein, metabolite
measuring microbiota using DNA
identifies which species are present - use next gen DNA sequencing
measuring microbiota RNA
measures abilities of microbiota by measuring activities and protein production - use RNA sequencing
measuring microbiota protein
measure proteins and produced by bacteria - mass spectrometry
measuring microbiota metabolites
measure metabolites produced by bacteria - mass spectroscopy