The Human Microbiome Flashcards
What is the human microbiome?
The collection of microbes, viruses, fungi and archea, and their genes in/on the human body.
How do microbial genes compare to human genes?
-Microbiome: 3.3 million genes.
-Human genes: 22,000 genes.
Define dysbiosis and give two examples linked to the disease.
Microbial imbalance due to IBD, obesity, diabetes, and autism.
Which phylta dominates the gut microbiome?
Bacteroidetes and Firmicutes.
Why is Helicobacter pylori notable in the stomach?
It colonises the stomach and is linked to ulcers and cancer.
What distinguishes the skin microbiome?
Low microbes on exposed areas, high in moist regions (eg, axilla) P. acnes causes acne.
What is the difference between 16s rRNA sequencing and shotgun metagenomics?
-16S: Targets Bacterial rRNA (taxonomic data).
- Shotgun: Sequences all DNA ( functional + taxonomic data).
What are the limitations of traditional culturing methods?
Only around 50% of bacteria are culturable, and it is labour intensive.
How do SCFAs benefit the host in the cell?
-Butyrate: Anti-inflammatory
- Fuels colonycytes
- Acetate/propionate: regulate immnunity.
How do bacteroides fragills influence immunity?
PSA polysacchride promotes regulatory T cells (Tregs) = immune tolerance.
What role does tryptophan play in the gut-brain axis?
metabolised to serotonin (mood) or kynurenine (immune regulation).
How do antibiotics disrupt the microbiome?
If overused, it can lead to dysbiosis (the imbalance of the microbiota) leading to diseases such as IBD and asthma. They also reduce the diverity of the microbiota.
What is the “hygeine hypotheis”?
Early life microbiome exposure trains immunity, and a lack of exposure may increase allergy/autoimmunity.
Name a microbiome diet interaction affecting obesity:
- High-fibre diets = improved insulin sensitivity.
- Low-fibre diets promote dybiosis.
How might fecal transplants treat C. difficile?
It restores healthy microbiota diversity to outcompete pathogens.
What is NLRP6’s role in colitis?
NLRP6 deficiency alters microbiota, which leads to increased colitis susceptibility (transferable to wild-type mice).
