Lecture 30 Flashcards
How many phyla?
- 92 bacterial phyla
- 26 archael phyla
Human MICROBIOME AIM
- to characterise microbial communities found at multiple human body sites and to look for correlations between chances in microbiome and human health
- five year project started in 2008
- used culture-independent methods of microbial community characterisation (16s and metagenomics) as well as whole genome sequencing of individual bacterial species
- emphasis on: oral, skin, vagina, gut, and nasal/lung
The HMP goals
- to delvelop a reference of set microbial genome sequences and perform preliminary characterisation of the human microbiome
- to explore the relationship between disease and changes in the human microbiome !!!!!!!!!!!!!!!!!!!
- to develop new technologies and tools for computational analysis
- to establish a resource repository
- to study the ethical, legal and social implications of the microbiome research
How many microbial species in the human microbiome
- 10,000
How many bacterial species in gut
500-1000 bacterial species just in gut
Human microbiome project showed that there was:
- strong niche specialisation both within and among individuals = different sites - different microbes
- diversity and abundance of each habitats signature microbes vary widely even among healthy subjects - unique microbiome between people - same bacteria but different stain
Microbiome diversity
- metabolic pathways of microbiome is consistent across humans
- one individuals gut bacteria have 50 times the genetic diversity of the human genome
- HMP documented 81-99% of the genera, enzyme families and communist configurations occupies by healthy western microbiome
- everyone has about 160 species (57 were really common)
- the community can change but the functions do not
- observed variations in both pathways and microbes changes with clinical metadata along ethnic/racial differences
What does the microbiome do for us?
Competition by commensalism microbes protects from pathogens:
- prevent pathogens form being successful
- blocking colonistation niches
- competing for nutrients
- modifying environment to change virulence factor expression
- making environment actively hostile; producing bacteroicins (anti microbial) + short fatty chain acids
- lowering pH
- cause host to thicken mucus layer
- cause host to up regulate anti microbial peptides (defensin, IgA)
- primes host neutrophils and macrophages
Different sites =
Different bacteria in healthy humans
__ bacterial phyla and __ archaeal phyla exist, but human microbial communities are dominated by _
92
26
4
4 dominating phyla
- firmicutes
- bacteroidetes
- actinobacteria
- proteobacteria
An estimated ____ - ___% of human- associated _____ are thought to have eluded cultivation so far
20-80
Microbes
___ bacteria groups, but ____ different ______ and _____
Few bacterial groups but many different species and strains
The human gut: a densely populated world of microbes (NOT CORE)
- human gut also known as: gastrointestinal tract and digestive tract
- highest density of microbes in human body - huge genetic and metabolic potential, varies in pH and oxygen
From oral cavity to anus - different environments and different conditions as u move down
- colon most densely microbal
- 50% of faecal biomass = bacteria
Different sites = different conditions
Differences in microbes reflect this
Some functions of the gut microbiome
- bacteria in gut breakdown cellulose (plant material) into products which are then used by other microorganisms ending up with further end products
- the gut micro bacteria creates SCFAs that modulate our metabolism and affects out defence against pathogens
Some (more) functions of the gut microbiome (vitamins)
The microbiome can: (normal, commensal bacteria - normally found in body, NORMAL MICROFLORA )
- synthesis vitamins including:
- B vitamins: B1, B6, B5 (pantothenic acid), B7 (biotin), B9 (folic acid), B12 (cocalamin)
- modulate the immune response
- alter drug delivery
Differences between probiotics and prebiotics
Good and bad bacteria
Good vs bad… C. Difficile vs lactobacillus paracasei
Two gut species: C. Difficile and lactobacillus paracasei
Bad - C. Difficile
Good - lactobacillus paracasei
- both use siallic acids from mucins (the main structural component of the mucus layer in the gut) as carbon/energy source —-> heterotrophs
- speed of growth and presence of accessory genes are the only factors making C. Difficile a pathogen
Fecal matter transplant
Fecal microbiata transplantation (FMT) is a highly successful treatment for multiple recurrences of clostridium Difficile infection (CDI)
