Microbial Communities and Human Health-Lecture 27 Flashcards
What is a biofilm?
Biofilms are surface attached, multicellular bacterial communities living in a self secreted matrix
What are Exopolysaccharides
An EPS is a substance secreted by the cell that acts like a glue to stick the bacteria onto the surface.
Where are biofilms prevalent?
In agriculture-> can promote crop production
In marine biofouling-> can stick to marine ships and decrease fuel efficiency
In medicine-> cystic fibrosis
Why are biofilms so prevalent in many different environment?
Safety in numbers
- > shared goods
- > metabolite exchange
- > communication
- > cohesion/adhesion
Protection against environment
- > antimicrobial resistance=> mechanical strength
- > environmental stress (host attacks)
What causes Cystic Fibrosis?
Mutation in the CFTR membrane protein, specifically the F808 amino acid (deletion mutation)
F808 is responsible for holding together the protein domains, and it still does this when its mutated, but when the body senses the mutation, F808 gets degraded
How does CFTR function in relation to Cl- and Cillia?
In normal cells, CFTR releases Cl- ions and calls water to cell surface=> loosens mucus and allows cilia to move bacteria
In mutated cells, CFTR does not release Cl- ions, no water to cell surface, build up of mucus mats down cilia, buildup of biofilm bc mucus is too sticky
What is a common CF treatment? What antibiotic is used and how does it work?
High frequency chest wall oscillation therapy with the antibiotic Tobramycin
High powered vest with antibiotic mechanically moves mucus in lungs
Tobramycin kills loosened bacteria that is no longer in biofilms
What bacterial species are prevalent in CF lungs throughout life?
In older people: P. Aeruginose
in Younger people: S. aureus
How does bacteria enter lungs and form biofilm?
Just by breathing and living=> CF patients have dominant species
How does bacteria build biofilm? Which protein regulates it?
Biofilm buildup is caused by the C-di-GMP protein which inhibits flagella formation.
when a cell surface is sensed, C-di-GMP halts flagella production and bacteria makes EPS instead
Bacteria aggregates on surface and forms microcolonies
Biofilm matures, becomes large and portruding
Environmental stressor triggers dispersion, C-di-GMP stops, flagella reformed, new surface found
How do microbes adapt to the environment they experience
P. Aeruginosa is an opportunistic pathogen, it only impacts immunocompromised individuals
Adaptations include:
- Loss of Motility
- Amino Acid Auxotrophy
- Loss of LPS-O-antigens
- alginate overproduction => leads to mucoid colonies
- Rugose Colony formation: rugose colony gets very wrinkly bc of EPS overproduction
How does mucoid form? How do mucoid impact CF patients?
P. Aeruginosa has an overactive stress response that produces the alginate operon, the operon is locked on by mutants.
The alginate operon will produce mucoid substance that is very sticky and goopy
In Mucoid cells, P. Aeruginosa takes advantage of the Ca+ in the lung to build bigger biofilm that is less susceptible to antibiotic=> prevents tobramycin penetration
What does the CFTR medication do? What is It called and what are its three domains?
The medication is called trifakta.
Tezacaftor and Elexacaftor helps CFTR folding, localization and function.
Iracaftor is the potentiator, it binds to CFTR to help it pump Cl- ions better.
