lecture 42: Human Bacteria Flashcards
What is the Microbiome?
- The complete collection of genes in the genome of all bacterial species (microbiota) that have co-evolved with human host (enormous genetic repository)
What is Microbiota?
- The individual bacterial species on our bodies in the biome
- We haven’t isolated and characterised every single bacteria that lives on our bodies
Describe the human microbiome project:
- Sequencing all the microorganisms that live in our bodies (nasal, oral, skin, gastro-intestinal, urogenital)
- Each community contains microorganisms from certain families and genera that are found in the same habitat in many or most individuals
- e.g. Lactobacillus found in everyone’s gut
- At a species and strain level: the microbiota of an individual can be unique as a fingerprint
- e.g. Some have lactobacillus reuteri (different strains)
What is the human microbiome project?
- A strategy to understand the microbial components of the human genetic and metabolic landscape and how they contribute to normal physiology and predisposition to disease
Number of microorganisms increase in the …
- Colon
There aren’t many _____ and _____ but lots of _____ and _____.
- Genera
- Phylum
- Species
- Strains
Two bacteria that dominate the gut:
- Firmicutes
- Bacteroidetes
Microbial species varies between ____, however are very _____ for an individual.
- Hosts
- “My stool is not your stool”
- Stable
Why is your fingerprint unique?
- Ecological interactions within hosts
- Host variability: diet, genotype, and environment
Function of gut microbiota:
- Intestinal development and function
- Metabolic function:
Breaking down toxins, xenobiotics, carcinogens
Synthesising micronutrients
Fermenting indigestible foods - Protects from colonisation by pathogens
Microorganisms have an impact on things like obesity? Do we acquire microflora that program us for obesity or normal weight?
- Microbes help in harvesting and sorting energy which benefitted us during early evolution (but now not necessary)
Human Obesity Facts:
- Transmisable, maternal obesity predisposes children to adult obesity
- Prevalence is increasing and has doubled
- Health consequences: type II diabetes, heart disease, cancer
- Causes: environmental, genetic, neural, endocrine
- Gordon wanted to look at the specific profile of gut microbiota
Gordon started his experiments on…he found out that…
- Mice, germ-free, born by C-section under sterile conditions
- Fed some a Western Style Diet, don’t weigh as much
- Massive weight gain in normal microbiota mice
- MICROBIOTA COMPOSITION CONTRIBUTES TO OBESITY
- Obesity is a transmissible trait (Microbiota)
What are the responsible microbes for obesity?
- Obese mice have 50% more Firmicutes and 50% fewer Bacteroidetes
- Able to change ratio with diet, BUT as soon as you go off the diet, normal microbiota ratio goes back to normal
- In obese mice, microbiota break down carbohydrates into short chain fatty acids which is your energy
Irritable bowel treatment:
- Normal faecal microbiota transplantation
- Safe and sometimes works!!
