Lab 5 - Biofilms, Quorum Sensing, and Bacterial Transformation Flashcards
What is a biofilm?
It is a complex aggregate of microbes that adhere to each other and to almost any surface (substrate) exposed to moisture, especially if there is another source of nutrition.
What are some examples of surfaces where biofilms can form?
Soil particles, water/sewage pipes, contact lenses, teeth, the throat, shower curtains, etc.
How can biofilms be beneficial?
Water purification and nutrient cycling.
What is a biofilm composed of?
Many different types of bacteria embedded within a self-produced matrix of spine, which is composed of extracellular polysaccharide, proteins, lipids, and DNA.
What is a planktonic bacteria? How do they differ from biofilm bacteria?
“Free floating” bacteria
They have different genes turned on, etc.
What sorts of things can affect gene regulation?
Cell density, specific cell surface attachment, temperature, types of nutrient, and sub-inhibitory concentrations of antibiotic
What is quorum sensing?
A type of gene regulation that depends on cell density.
What bacteria use quorum sensing?
P. aeruginosa, S. aureus, B. pertussis, and V. cholera
Why is the link between biofilms and quorum sensing important?
Inhibition of invasion until there are enough cells
And protection from antibiotics
What is transformation?
The genetic alteration of a cell resulting from the direct uptake and incorporation and expression of exogenous DNA from its surroundings.
Describe one way a superbug can be formed.
Since bacteria lyse in the biofilm, they release their DNA. This could cause bacteria to take up the DNA and potentially incorporate several virulence factors into its genome and then express them.
How can bacteria be protected from antibiotics?
By being part of a biofilm
Uptake of plasmids from environment
What is a plasmid?
Autonomously replicating circles of DNA
What is an R plasmid?
A plasmid that can make a bacterium resistant to an antibiotic
What kind of bacteria did we use when we transformed E coli to be bioluminescent? Why?
Bacteria in the log phase.
Because in the log phase, they are more susceptible to inducing competence.
