Buffl
Buffl
Bakterien

1) Microbes & Humans

PP
von Pia P.

List some of the key / historical scientists that have contributed to our knowledge of the microbiome

  • Hippocrates of Kos

  • Antonie van Leeuwenhoek

  • Elie Metchnikoff


  • What is the ratio of microbial to human cells?

  • What are the body sites known to harbour a microbiota?


  • 1.3 x 1 bacterial to human

  • Known body sites:

    • nose

    • mouth

    • ear

    • lungs

    • stomach

    • large / small intestine

    • urinary tract

    • vagina

    • skin


Definition: Microbiota


Community of microorganisms

  • bacteria

  • fungi

  • algae

  • archaea

  • protists


Definition: Microbiome

Microbiota + Microbial structural elements + Internal / external structural elements




Briefly describe some of the key benefical functions of the microbiota for the host health

  • Digestion and nutrition: helps break down complex carbohydrates, synthesizes important vitamins

  • Immune system modulation: stimulates the immune system, helps maintain its proper function

  • Regulation of metabolism

  • protection agains disease


Name the 4 main bacterial phyla of the human microbiota

  • Bacillota

  • Pseudomonadota

  • Actinomycetota

  • Bacteroidota


Briefly describe or draw the structure of human skin, and list the dominant microbiota members (Gram-positive and Gram-negative)



Top gram positive:

  • Staphylococcus spp

  • Corynebacterium spp

  • Micrococus spp

Top gram negative:

  • Roseomonas spp

  • Pseudomonas spp

  • Acinetobacter spp


List factors that influence the composition of the skin microbiota + 2 dominant species that colonise the skin longer-term

Extrinsic factors:

  • lifestyle

  • hygiene

  • routine

  • use of drugs and cosmetics

Intrinsic factors:

  • genetics

  • aging

  • sex

  • site of the body


Dominant species:

  • Cutibacterium acnes

  • Staphylococcus epidermis



Name the different “habitats” in the oral cavity that microbes colonise

  • teeth

  • tongue

  • cheek

  • lip

  • hard and soft palate

  • gingival sulcus

  • attached gingiva


List the most common bacterial genera in the oral microbiota

  • Veillonella (25%)

  • Neisseria (15%)

  • Streptococcus (10%)

  • Prevotella (10%)



Briefly describe the process for biofilm formation on enamel


1) Initial Attachment:

  • microorganisms in the mouth adhere to enamel surface

  • facilitated by pellicle formed from salvia

2) Microcolony Formation:

  • attached bacteria begin to multiply —> form small clusters

  • produce extracellular polymeric substances (EPS) —> creates a matrix that binds the cells together

3) Biofilm Maturation:

  • more bacteria adhere + produce EPS —> biofilm matures

  • —> develops complex 3D structure

4) Dispersion:

  • some cells or clusters detach from biofilm

  • —> spreads colony to new sites of enamel / other surfaces



Briefly describe the process for the microbial consortium forming a hedgehog structure on plaque

  • Spatial organization of microbes

    • Corynebacterium (violet): spiny, radially oriented filaments

    • Streptococcus (green): outer shell

    • Less O2 at base of structure -> anaerobic bacteria (white)



List the different physiological structures that make up the respiratory tract

  • nasal cavity

  • nasopharynx

  • oropharynx

  • trachea

  • lung


List some of the important bacterial taxa in the nasal microbiota and what % of humans harbour S. aureus

Most important bacterial taxa:

  • Bifidobacteriums

  • Corynebacterium

  • Staphylococcus

  • Streptococcus

  • Dolosigranulum

  • Moraxella


What are the issues with sampling the lung microbiota + what bacterial genera colonise the lung


Issues:

  • contamination issues due to its complicated structure, only invasive possible

Bacterial genera:

  • Prevotella

  • Streptococcus

  • Veillonella

  • Neisseria

  • Fusobacterium


What bacteria genera colonise the genitourinary tract

What factors impact microbiotica composition

Urinary tract:

  • Lactobacillus, Corynebacterium, Prevotella, Staphylococcus, and Streptococcus

  • high variability between individuals and males vs feamles

Vaginal microbiome:

  • dominated by a limited number of lactic acid bacteria

  • Influenced by genes, ethnic background, environmental-behavioral factors


What is the most densly colonised body site?

List the different niches for microbial colonisation

Gut

Niches: Speichel, Speiseröhre, Magen, Dünndarm Dickdarm

Describe the ecological succession of the gut microbiota over the human life course

Describe some of the factors known to influence the early life gut microbiota and what bacteria genera dominate the infant gut microbiota

new-born microbiota closely matches the maternal stool, vaginal, or skin microbiota, depending on delivery mode


First colonisers are typically facultative anaerobes such as Lactobacillus and Streptococcus, and E. coli – help reduce the aerobic environment

list 10 examples of microbiota members that live in the adult gut

  • Bifidobacterium

  • Faecalibacterium

  • Clostridium

  • Ruminococcus

  • Bacteroides

  • Prevotella

  • Akkermansia

  • Escherichia (i.e. E. coli)

  • Alistipes


Provide examples of factors that influence adult gut microbiota composition and provide names of disease associated with microbiota disturbances

Factores: Diet, ANticiotics, Birth mode, Infections, Genetics

Diseases:

  • Internal Disease: Crohn’s Diseas, Colon Cancer

  • Metabolic Diseases: Diabetes, Obesity, Malnutrition

  • Autoimmune Disease: SLE, Type 1 diabetes

  • Brain-linked Conditions: Depression, Anxiety, IBS, Autism

  • Immune Disease: Asthma, Ezcema, Rhinoconjunctivitis, Food Allergy


Name and describe 3 microbial/diet strategies that can be employed to manipulate the gut microbiota (i.e. pro-, pre-biotics and FMT)

Prebiotics, Probiotics

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Author

Pia P.

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