Topic 8

Question 1

When might chemostats be used and what phase of growth do they show?

Answer 1

used when conditions need to mimic environmental conditions but also need to be highly controlled; culture stays in log phase

Question 2

What is a chemostat culture system?

Answer 2

an open culture where equal amounts of medium is added and removed

Question 3

What are the 5 steps of biofilm formation?

Answer 3

1) attachment of planktonic bacteria
2) sessile bacteria from microcolonies
3) EPS is secreted
4) towers, channels, and microenvironment form
5) Dispersal

Question 4

What are single species biofilms associated with?

Answer 4

disease-causing biofilms

Question 5

Describe the process of Quorum sensing.

Answer 5

Controls density of communities and biofilms. Bacteria secret autoinducers into their surroundings, as the concentration of cells in an environment increases, the [autoinducer] increases as well. When the environment reaches a certain [autoinducer], the autoinducers bind to transciption regulators and bind to DNA to turn on quorum sensing genes

Question 6

Why are biofilms hard to remove?

Answer 6

they have different microenvironments on the surface and dormat cells deeper in the film

Question 7

What are endospores?

Answer 7

a product of G+ cell differentiation

Question 8

What are heterocysts?

Answer 8

a product of cyanobacteria differentiation that is sensitive to O2 because it houses the nitrogenase enzyme

Question 9

What are arthrospores?

Answer 9

the product of actinomycete bacteria differentiation that are resistant to drying

Question 10

What are fruiting bodies?

Answer 10

a product of cell differentiation of myxococcus xanthus