Microbiome Flashcards
What are the two main bacteria phyla in most people?
Phyla Bacteroidetes (Which are Gram Negative) and Firmicutes (Which are Gram Positive)
How much bacteria does the colon contain?
10,000 times more than the small intestine
What is the largest factor in microbiome composition?
Diet
What does “gnotobiotic” mean?
It means “Known life”. For the context of this exam, it refers to a mouse that has been colonized with a known set of bacteria.
What are the three types of mouse models that are used to study microbiota?
Gnotobiotic, Germ-Free, and Humanized
What does “Germ-Free” mean?
The mouses gut is devoid of any bacteria
What does “Humanized” mean?
The mouse gut has been colonized with human microbiota
What is meant by the term “Microbiota Plasticity”?
The ability of microbiota to adapt as a response to changes in its environment (Ie changes in diet result in changes in composition)
What is the bacterial representation when ingesting 100-150g of fibre?
UP- Prevotella, Eubacterium
DOWN- Bifidobacterium
What is the bacterial representation when ingesting 10-20g of fibre?
DOWN- Prevotella, Eubacterium
UP- Bifidobacterium
Having greater levels of Prevotella and Eubacterium, and lower levels of Bifidobacterium results in what health effects?
Decreased rates of infectious,metabolic, inflammatory disease, and nutritional deficiencies
Having lower levels of Prevotella and Eubacterium, and higher levels of Bifidobacterium results in what health effects?
Higher rates of metabolic, inflammatory disease, diabetes, obesity
Why can’t formula imitate breast milk?
1) HMOs are too complex to manufacture or extract
2) Probiotic Composition of breast milk is unclear
3) Personalized antibodies are impossible to reproduce
Mouse model studies of multiple sclerosis have shown:
- Germ-free mice have reduced ability to stimulate T-cell responses, while colonized mice show increased T-cell responses
- Gut bacteria can regulate pro- and anti-inflammatory immune responses in the central nervous system
B Cells and T Cells ->
Pro-Inflammatory
T-Regs
Anti-Inflammatory
Hygiene hypothesis?
A lack of early childhood exposure to
microorganisms (beneficial or infectious) suppresses the natural immune system and leads to an increased risk of allergies
Colonization resistance
the mechanism by which the gut microbiota
protects against pathogenic infection
Decreased exposure to microorganisms is due to:
Oversanitization (antibacterial soaps, hand sanitizer, etc.)
• Separation from traditional lifestyles (farming, foraging, etc.)
• Overusing antibiotics
Probiotics?
- Are transient and do not permanently colonize the gut
- Most conventional probiotics are not well-suited for the gut environment
- Serve as dummies to keep the immune system alert, and to reinforce the gut’s protective lining
Prebiotics?
indigestible carbohydrates used to promote the growth of beneficial microbes in the gut (ie. insoluble fibre)
Synbiotics
synergistic pairing of pre- and probiotics toward an augmented health outcome
The human genome only contains genes for the breakdown of 3 simple
sugars:
starch, lactose, sucrose
The microbiome contains the missing genes required to digest the carbohydrate structures of the plant cell wall:
hemicellulose, pectin, and animal glycans (mucin)
