The human microbiome

Question 1

Aspects which impact on the human microbiome

Answer 1

1. Age: microbiome develops alongside age
2. Diet: Big involvement. It adapts to your diet
3. Genetics: Determines what receptors we have and if we secrete certain metabolites that can interact at a metabolic level with the microbiome
4. Lifestyle: Sedentary or active will affect microbiome
5. Environment
6. Immune response: tuned exposure and how it was developed will affect microbiome development
7. Microbial co-adaptation: Having a lot of one species, the microbiome will adapt so they can live together compared to another species which are scarce to me

Question 2

How does the microbiome play a role in control of homeostatic mechanisms in the body

Answer 2

1. Protection against pathogens
2. Synthesis of vitamins: the microbiome can synthesise Vit K and B12 for us to take up
3. Immune system development
4. Promotion of intestinal angiogenesis
5. Promotion of fat storage
6. Short chain fatty acid production by fermentation of dietary fibre: microbes can help digest this fibre, ferment it and give rise to SCFA
7. Modulation of CNS

Question 3

How can the microbiome prevent a pathogen from being successful. Direct and indirect mechanisms

Answer 3

1. Direct mechanisms:
   - Nutrient competition: microbiota take up nutrients so the pathogens struggle to establish itself. Compete for salicylic acid, fructose.
   - Direct toxicity: strategies to kill incoming bacteria. Biofilm, bacteriocin and type IV secretion
2. Indirect mechanism
   - Immune induction: commensals help the immune system to be optimally prime to deal with a pathogen
   - Metabolic products: Sort of links to direct toxicity, refers to metabolising certain host factors such as bile salts, this change impacts certain bacteria as they miss certain triggers and certain nurtrients

Question 4

Define the terms dysbiosis, probiotics and prebiotics

Answer 4

1. Dysbiosis: Imbalance of normal gut microbiota composition. Quantitative/qualitative, metabolism etc… These changes result in harmful effects on the host
2. Probiotics: Non-living organisms used as food ingredients to benefit the hosts’ health
3. Prebiotics: Non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improving the hosts’ health.