Microbes-L5- Microbiomes and Health

microbiota vs microbiome

microbiome- collection of bacteria, viruses- everything- the genetic material in an environment

microbiota- ecological community of microorganism

what do different niches of microbiomes diffe

• percentage of oxygen

• humidity

• nutrient rich/nutrient poor

what are the human microbe composed of?

1m genes

23k human genes

99% of our genes are in microbial cells

discuss the gut commensal ie the abundance of microbiological matter in the intestine?

• 2kg of body weight

• 60% dry weight of faeces

• have both good and bad bacteria

4 dominant phyla in the gut composed of?

1. bacteroidetes

2. firmicutes

3. proteobacteria- abundant is everything

4. actinobacteria

what does the gut microbiota do in the body?

1. digestion aid- ie breakdown of complex carbs and production of short chain fatty acids

2. gut immunity

3. behaviour(?)

your gut microbiome affects your susceptibility to infections

what are some genomic approaches to study microbiota? and why?

1. metagenomics

2. 16s rRNA sequences

3. metatranscriptonomics

needed as there are limitations as some bacteria do not grow on plates

how is the composition of microbiota influences?

1. diet

2. exercise

3. ageing- massive shift as we get older

4. antibiotics

5. geography- exposed t different environments and foods

6. birth mode- breast fed/formula fed

how is the shaping of our microbiome done in early development?

mode of birth

• vagina- 2 bacteria colonise babies- lactobacillus and bifidobacteria

• c section- staphylococcus and propionibacterium

<1 year

• great fed or formula fed

• breast milk- lactobacillus and veillonella

• solid food- bacteroids, clostriadeles

1-3 years

• full adult diet- full adult microbiota

breast milk vs formula feeding- differences

• breastfeeding- has bifidobacterium- very important and strengthens microbiota

what bacteria takes over when unhealthy vs healthy?

• healthy- 4.5% of proteobacteria

• unhealthy- 14.9% in inflammation and cancer

germ free mice studies- what did it show?

• germ free mice has defects

• in lymphoid tissues and

• decrease mucous secretion,

• no mucus secretion

• no TLRs exposed

• B cells in the spleen- important for adaptive immunity

no microbes means poorer development of the immune system

why are humans not germ free?

microbes help digest food by breaking it down

microbes train our immune system- telling them to destroy bacteria- when there’s a second encounter

discuss the intestinal epithelium in the gut

largest mucosal surface and is composed of a single layer of epithelial cells

• has endocrine cells for hormones

• has goblet cells- secrete mucin

• has enterocytes for absorptive cells

• and panted cells to produce AMPs

discuss the function barrier of the gut- what happens when it is compromised

has antimicrobial peptides- AMPS- anti fungal and antibacterial

Mucus has peptide A- to help binds and protect from pathogens

when compromises- DYSBIOSIS- lack of balance which can cause- leaky gut, IBD, allergies, food intolerance

discuss the gut mucus later

• secreted by goblets cells

• sticky to keep a pathogen in place

• mucus has glycoproteins-mucins

• has antibodies and macrophages

separates epithelium from gut LUMEN

discuss AMPs in the gut

• small proteins in the innate immune system

• found in the intestinal epithelium- by PANETH cells

• produced in response to infection

how does lifestyle influence microbiome in childhood?

macrobiotic depletion theory: hygiene hypothesis- lack of early childhood exposure to infectious agents increases susceptibility

• to allergic diseases and less development of the immune system

what a probiotics and how do they enhance gut health?

• non pathogeneic

• human origin

• resist gastric juices

• attaches to epithelial cells

• colonises intestinal tract

how do fecal microbiota transplantation work?

transfer a healthy donor sample to a patient to introduce and restore state microbial community in the gut

• usually in C.diff patients

how do antibiotics kill good and bad bacteria?

they aren’t selective and can take up to 6 months to restore gut microbiota

• UTIs can occur- clear out protective bacteria- e.coli from the gut overgrows and invade urinary tract

• leaky gut- antibiotics weaken tight junctions between intestinal cells

• c. diff infections- antibiotics trigger C diff

• IBD- linked to a lack of breast feeding