Lecture C7 - Fungal Collaborators and Competitors Flashcards
What is mutualism?
Both microorganisms derive an advantage from one another.
Describe commensalism.
One of the microorganisms provides an advantage to the other without deriving a positive effect for itself.
Describe amensalism.
One of the microorganisms has a negative effect on the other while it remains unaffected.
Describe parasitism.
One of the microorganisms (parasite) benefits at the expense of the other (host).
Describe competition between microorganisms.
Negative effects for both microorganisms.
What are some examples of negative bacterial:fungal interactions?
P. aeurginosa and S. aureus with C. albicans.
R. faeces and R. intestinalis with C. glabrata, C. tropicalis and S. cerevisiae.
Describe the interaction between Candida albicans and Pseudomonas aeruginosa.
Grow together in burn wounds and in cystic fibrosis.
Negative effects on each other - P. aeruginosa adheres to the fibres of the C. albicans and kills the hyphae.
Release things that inhibit biofilm formation.
Prevent candida from going from the yeast form to the invasive form > good for us but not for the yeast.
Describe the effects of phenazines.
Pyocyanin stops the wrinkling phenotype and makes them smooth > alters the growth of the hyphae.
Biofilm formation also affected.
Form a biofilm then add the phenazines in there is a lesser red colour > affecting the respiration of C. albumins.
Describe the interactions between Lactobacillus and C. albicans.
Grow and produce lactate, C. albicans makes immunogenic b-glucan. Doesn’t want to cause disease just wants to grow.
Can compete for adhesion sites, pH that lactate generates degrades candida cell wall preventing it from colonising - not in a pathogenic state which is good for the human host.
Describe the type 6 secretion system and microbial competition.
Type 6 secretion system in gram negative bacteria is like a needle.
Tip of the needle goes into the target cell and releases toxins into the cell, special effectors fused onto the tip of the injector cell.
Contracts and fires toxins into the target cell, if you are susceptible you suffer from the effects of the toxins. However, most of the time there is immunity proteins which means the toxin can’t kill the cell.
Name some T6SS effectors.
Inter-bacterial killing and growth inhibition.
Nutrient scavenging.
Host colonisation (virulence).
T6SS induction by the host niche.
Host colonisation (symbiosis and biocontrol).
T6SS induction by microbiota.
Acquisition of genetic material.
Intraspecies social control.
Kin discrimination.
Killing of microbial eukaryotes.
What is Serratia marcesens?
Gram negative bacterium.
Ubiquitous in environment.
Opportunistic pathogen of humans in UTI, RT, wounds and eyes.
Likely lives in many poly-microbial communities.
Multiple anti-bacterial effectors in the T6SS.
Has antifungal activity.
What is lysis of C. albicans dependent on?
Tfe1
What are granular structures dependent on?
Tfe2
What growth arrests when you induce Tfe2?
S. cerevisiae but can be reduced when Tfe2 is removed.
