4. Genes, regulation and communities Flashcards
what is an example of a positive interaction?
cyanobacteria with a heterotrophic bacteria present will survive longer
what is an example of a negative interaction?
Penicillium produces antibiotic which targets other microbes
What is an example of competition?
Sulphate reducing bacteria outcompete methanogens for substrates.
In quorum sensing, what does an autoinducer do?
senses population size
when it reaches a threshold cells respond which causes changes in expression and function
What is the quorum sensing system used by staphylococcus aureus?
Agr system
What does Agr express and what do they do? 4
Agr D - autoinducing peptide (AIP)
Agr B - transmembrane protein, secretes mature AIP
Agr C - Aip receptor, binds AIP and phosphorylater Agr A
Agr A - response protein - induces RNA III
What does RNA III do? 2
represses adhesion and induces invasion elements
Which organism can form biofilms on contact lenses and what might this cause?
S. epidermis
keratitis
Which organism form biofilms on urinary catheters and what might this cause?
E. coli
Bacteriuria
Which organism can form biofilms on joint replacements and what does this cause?
S. aureus
Septicaemia
What are the 5 stages of biofilm development?
- initial attachment
- irreversible attachment
- maturation I
- maturation II
- dispersion
What does twitching motility in Pseudomonas aeroginosa entail? 3
express type IV pili
induce alginate production
repress flagella expression
What is the twitching motility linked to?
sigma factor 22
what is important for Vibrio parahaemolyticus maturation?
a switch between two flagella systems - secondary system is linked to swarming motility
