Microbiota

FNN Midterm

Microbiota

• community of microorganisms living in a specific environment

Microbiome

• microorganisms and their genes in a particular environment

Metagenome

• the genes of microorganisms in a specific environment 

Human Microbiota and where it comes from 

• Birth - earliest exposure 

  • feeding and how you were delivered impacts how what is in the microbiome

• environment - dust, pets, air

  • varies by geographical location

• Antibiotics/medications can alter what is a part fo the microbiota

• host genetics

• age

• GI disease and inflammation

• Diet

• Lifestyle and physical activity

Intestinal Microflora

• Stomach: Lactobacilli

• Duodenum: Streptococci and lactobacilli

• Jejunum: Enterobacteria, enterococcus, facelais, bacteriodes, bifidobacteria

Spread of the intestinal microflora

• increase as you move down the digestive system

• least in stomach

• most in the colon and appendix/large intestine

Gut microbiota in different regions

• there is no single definition of a healthy microbiome 

Pro and prebiotics

• probiotics are bacteria which promote optimal digestion and absorption of nutrients whcih promote healthy digestive tract 

• prebiotics 

Provatella species

• found mostly in african and asian countries 

• from fibrous foods

Sources of beneficial bacteria -

• fermentible, non digestibel carbohydrates 

• resistant starches are prebiotics 

• Results of fermentation of bacteria is short-chain fatty acids which produce and environment more favourable for 

US immigration and microbiome

• in a study of multigenerational women

  • stool samples 

• there was a loss in bacterial fiber degrading enzymes 

• loss of microbial diversity 

  • DYSBIOSIS 

• loss of microbial diversity compounded by obesity 

• Prevotella strains were significantly lower the longer one had been in america 

• Bacteriodes were larger 

  • poor diversity 

Dysbiosis

• imbalance in the microbiota that results in detrimental effects such as inflammation and impared immune function 

symbiosis

• more beneficial bacteria than pathogens

  • unhealthy diet may push this to disbiosis 

• healthy diet, probiotics, prebiotics can help to have symbiosis 

Gut environment and host health

• good health the epithelial barrier is strong and prevents the unhealthy bacteria from entering the system 

• disease

  • excess inflammation 

  • altered immune function 

  • damaged epithelial barrier 

Prebiotics feed probiotics

• prebiotis are foods whcih stimulate the growth or activity of healthy bacteria in the colon

  • fibers, resistant starch, supplements

• Probiotics 

  • live micro-organisms

  • most common are lactobacillus and bifidobacterium 

  • must contain 100 million live bacteria 

  • transient effect - must be taken continuously 

    • eg. feremented foods 

yogurt

• bifidobacterium and lactobacillus are examples of probiotics

How does diet fuel gut microbiome

• fermentabel fiber = fuel 

  • pectin, B-glucans (oats), inulin, resistant starch 

• In the gut microbiome these becomes SCFAs 

  • acetate

  • propionate 

  • butyrate

SCFAs

• acetate 

• propionate 

• butyrate 

Roles of SCFAs

• improve nutrient absorption 

• increase bile acid excretion 

• decrease secondary bile acid formation 

• enhance mucosal barrier protection 

• increase the growth of health promoting bacteria 

• inhibit growth and adhesion of pathogens 

Gut brain axis

• gut brain connec tion is liek a highway or phone line 

Tedtalk video

• diet impacts on mood

  • Triptophan makes melatonin and serotonin 

    • alone they cannot cross blood brain barrier but triptophan can which allows them to create serotonin in the brain

  • Tyrosine → dopamine

• Lethal to microbiome

  • stress, alcohol, antibiotics

Gut brain communication

• nervous system → vagus nerve, neurotransmitters

• Immune system → cytokines

• endocrine system → gut hormones, brain hormones

• Microbiota products → SCFAs

FMT 

• fecal microbiota transplant 

• can help to improve depression symptoms by transferring from anothers microbiome

• mental disorders oftan accompany changes in microbiota composition

• studies are inconsistent about which bacterial species are involves

• factors that affect the gut-brain acces affect mood disorders