Special Adaptations-lecture 24 Flashcards
What are the different types of motility?
Swarming- involves cellular differentiation and surfactant production
swimming- doesn’t involve surface
twitching: involves type IV pili- cells move slow, produce a twitchy motion
- pili reach out and attach to surface and pull
Gliding: Prok has focal-adhesion complexes on cell surface
Sliding: spread by growth-> secrete surfactant that allows for gliding
Types of surface motility and model organisms for each, gliding and twitching motility
Gliding motility: focal adhesions basically motor power bacteria making the cell surface to provide traction
- focal adhesions oscillate around bacteria
- model organsims: Cytophaga Sp.
Twitching motility: Extend/retract pilus-> pulls body along
- pilin is the pills subunit
- model organism: pseudomonas aeruginosa
What is the molecular model for type IV Pilus function (twitching motility)
pilin subunits polymerize to form pilus extension
depolymerase disassembles subunit and causes retraction
Mutants in PillT causes no retraction
Describe Twitching motility in P. Aeruginosa
Twitching motility in P. Aeruginosa leads to formation of an exopolysaccharide tail
- > leaves EPS stain in its wake
- > when P.Aeruginosa bunds into EPS stain trail, they either stop moving or follow trail
- Pill A mutant strain does not produce trails
Twitching Bacteria tends to follow the trail
–> Increases the likelihood of bacteria to encounter each other on a 2-D surface and form aggregates
What is swarming motility?
Flagella-driven group motility on a surface-usually involves surfactant
–> surfactant is a self induced agent to make surface slippery
In some bacteria, swarmer cells are longer and have more flagella
In other cells, swarmer cells have distinctly different flagella compared to swimmers
—> Phylogenetically widespread, bacillus subtitles can do it too!
What are some common surfactant structures? THINK : LUBE
Bacillus Subtilis uses a surfactin
Pseudomonas aeruginosa uses a rhamnolipid
serratia liquefaciens use lipopetides (surfactin and serrawettin)
Not all swarming bacteria produce surfactants (E.coli do not)
They are amphipathic (hydrophobic and hydrophilic)
they reduce surface tension between cell and surface
regulated by quorum sensing
What are common traits of swarming bacteria?
- The swarming lag: Bacteria do not swarm immediately
- > to exit the lag, bacteria must:
- high cell density
- hyper flagellation
- nucleation/raft formation (cellulose fibrils) - Cell elongation/hyper flagellation
- Colony pattern Formation (bulls eye petri format)
- proteus bacteria have consolidation zones with bursts of growth and movement
Flagella of Vibrio parahaemolyticus
Free swimming flagella:
Sodium driven polar flagellum encoded by Pof, is very long
Surface flagellum:
H+ polar head
lateral flagella encoded by Lab gene-> is thinner and shorter than free swimming flagella
How to differentiate flagellum into light?
Use laf-lux transcriptional fusion to create bioluminescence with the enzyme luciferase
What are the key factors impacting flagella expression?
Viscosity- impedes flagellum rotation
antibody agglutination-exerts force on flagellum that can create light in non-viscous mediums
Conclusions: Antibiotics that tether Pof or high viscosity lead to differentiation from Na+ flagellum to H+ flagellum
Slow motor rotation or low viscosity causes differentiation into the H+ flagellum
How does phenamil impact flagellum?
Phenamil is a sodium channel blocker that will decrease rotation in Na+ flagellum
Impaired turning of basal body-> decrease swimming speed
What is the relationship between swimming speed and laf induction?
A decrease in polar flagellar rotation rate, rather than external force applied against flagellum, triggers swarmer cell differentiation
Spirochete motility
spirochetes are a corkscrew bacteria that are found in viscous parts of the body (found in dental plaque and Syphillis)
Theres an endoflagellum that wraps around the body on the outside, rotates around protoplasmic cylinder
What is a magnetosome and magnetotaxis?
Magnetotaxic bacteria are gram negative bacteria that thrive in microbic conditions
Move faster as field strength increases
move parallel to magnetic field
integrated with aerotaxis(moving in relation to oxygen gradient)
Purpose: help bacteria find toxic-anoxic interface in aquatic systems
Aerotaxis counteracts magnetotaxis when magnetoxic bacteria buries too deep
Explain about gas vacuolated bacteria
Gas vesicles can be produced by eubacteria and archaea and are used by phototrophs to move them up and down the water column
Contain proteins to arrange a gas-permeable, but watertight structure
In phototrophic bacteria, gas vacuoles are mainly in phototrophic bacteria and maintain position depending on sun, move away from sun
