Biofilms

Question 1

What are biofilms

Answer 1

Multicellular, multilayered, populations embedded in a polysaccharide matrix attached to a solid surface

Question 2

What is biofouling?

Answer 2

undesirable accumulation of microbes, plants + small animals on artificial surfaces

Question 3

Explain the formation of biofilms

Answer 3

1) bacteria attach to the surface: reversible formations
2) extracellular matrix forms: irreversible attachment
3) grow: stage one maturation
4) want media to flow through towers: stage two maturation
5) cells inside can swim away: dispersion

Question 4

What is confocal microscopy?

Answer 4

-used to study big things (like plant)
-laser scanning microscope
-comparing multiple layers
-uses point illumination + a pinhole in an optically conjugate plane
-acquires images of what amounts to thin sections allowing 3-D reconstructions of solid objects such as biofilms

Question 5

How does flow cell work?

Answer 5

-media moves around
-biofilm will not grow w/out movement
-cells that stay are a part of the biofilmH

Question 6

How does microtiter dish (colorimetric assay) work?

Answer 6

-grow bacteria in polystyrene (plastic that biofilm bacteria love) microtiter dish
-after the growth period wash out well
-stain adherent bacteria w/crystal violet
-determine density using a spectrophotometer

Question 7

role of type Iv pili

Answer 7

structure on the cell surface that are known to be required for both adherence to surface and twitching motility

Question 8

what is fliP

Answer 8

gene thought to be involved in flagella biosynthesis
-mutations lacking flagella were unstable to attach to the PVC surface

Question 9

How do biofilms contribute to antibiotic resistance

Answer 9

-nutrient depletion creates zones of altered activity
-inner layers of biofilms cells have more time to initiate stress response
-free floating cells neutralize the antimicrobial agent
-free floating cells spawn protected persisted cells
-biofilm multicellularity results in better bacterial defenses

Question 10

What effect does high cell density have

Answer 10

make biofilms the perfect environment for horizontal gene transfer

Question 11

What is the role of the Tb gene?

Answer 11

-Tb binds to sites on the 30S and 50S ribosomal subunit, preventing formation of the ribosomes + blocking translation

Question 12

What are two regulating factors of biofilm formation

Answer 12

1) The bacterial cells attach to a surface activation of molecules required for surface attachment such as pili + adhesins
2) after attachment, the bacteria come together to form microcolonics.

Question 13

What are the steps of disease

Answer 13

-colonization -> biofilms
1) planktonic bacteria are vulnerable to antibiotics and phagocytes
2) bacteria form biofilms on inert surfaces
3) phagocytes are attracted to the biofilms. Phagocytosis is blocked but phagocytic enzymes are released
4) phagocytic enzymes damage tissue around the biofilm
5) bacteria are released from the biofilm. Dissemination can lead to infection in neighboring tissue