Biofilms

Question 1

How can bacteria grow?

Answer 1

Free-floating
Sessile
Biofilms

Question 2

What is the biofilm structure?

Answer 2

Composed of polysaccharide-protein and DNA
The matrix encases the cells within it and facilitates communication among them through biochemical signals as well as gene exchange

Many microbes
Heterogenous
Protective

Question 3

What are the extracellular polymeric substances?

Answer 3

Crucial for biofilm formation 
Long polysaccharides composing of:
-alginate 
-poly-N-acetylglucosamine 
-sucrose-derived glucans and fructans 
-xanthan 
-cellulose
Is a DNA component

Question 4

What are the functions of biofilms?

Answer 4

Adhesion
Protection 
Hydration 
Energy 
Nutrients 
Exchange of genetic information

Question 5

What is quorum sensing?

Answer 5

A system of stimulus and response correlated to population density
-causes coordinated changes in the phenotype of all cells in a population

Question 6

What happens when there is low cell density?

Answer 6

Low concentration of autoinducer because there is no transcription of target genes

Question 7

What happens when there is high cell density?

Answer 7

High concentration of autoinducer because there is transcription of target genes

Question 8

Quorum sensing and Pseudomonas aeruginosa

Answer 8

Opportunistic pathogen
Uses quorum sensing to coordinate virulence, biofilm formation, swarming motility, and exopolysaccharide production
Grows without harming its host until it reaches a threshold concentration
Protected against host immune defences

Question 9

What are some bacteria that can detect AHL but not produce it?

Answer 9

E. coli

S. enterica

Question 10

How is biofilm regulated?

Answer 10

by cyclic di-GMP