2016/2017 - Essay 2

Question 1

P1- Alkaline metabolism

For 2 named pathogens, compare the molecular mechanisms by which alkaline metabolism permits their colonisation on biotic and abiotic surfaces

Answer 1

Production of basic metabolic end-products
Role in the colonization of biotic and abiotic surfaces by certain pathogens

Pathogens
1. Vibrio cholera
2. Pseudomonas aeruginosa

Question 2

cholera, abiotic, biotic

Paragraph 2

For 2 named pathogens, compare the molecular mechanisms by which alkaline **metabolism permits their colonisation

on biotic and abiotic surfaces.**

Answer 2

Cholera
- Vibro cholera
- gram-negative
- severe diarrheal disease affects millions globally
- Aquatic environments
- colonizes biotic surfaces = chitinous exoskeletons ofzooplankton and intestines copepods

Abiotic
- V.cholera produce metabolic end products = ammonia, bicarbonate
- why> maintain high pH microenvironment> growth and colonization

Biotic
- produces virulent factors= toxin-regulated pilus (TCP) and cholera toxin
- > mediates attachment and biofilm formation

Question 3

Abiotic surfaces

Paragraph 3

For 2 named pathogens, compare the molecular mechanisms by which alkaline **metabolism permits their colonisation

on biotic and abiotic surfaces.**

Answer 3

Abiotic surfaces
- medical devices
- uses alkaline metabolism -> colonize + biofilm
- Extracellular matrix component= **Vibrio polysaccharide (VPS) and RbmA protein **
- > mediates attachment and biofilm formation
- alkaline end product - maintain high pH: growth and biofilm formation

Question 4

Pseudomonas aeruginosa, where is found, end-products

Paragraph 4

For 2 named pathogens, compare the molecular mechanisms by which alkaline **metabolism permits their colonisation

on biotic and abiotic surfaces.**

Answer 4

Pseudomonas aeruginosa
- gram negative
- hospital acquired infection
- immunocompromised patients
- cystic fibrosis patients

Where is it found?
- soil
- water
- hospital surfaces

End-products
- ammonia
- pyruvate
- >pH maintain: growth and colonization

Question 5

Pseudomonas aeruginosa , biotic surfaces

Paragraph 5

For 2 named pathogens, compare the molecular mechanisms by which alkaline **metabolism permits their colonisation

on biotic and abiotic surfaces.**

Answer 5

Pseudomonas aeruginosa - Biotic surfaces
- Respiratory tract of cystic fibrosis patients
- Produce virulence factors: Type IV Pili and expolysaccharides
- >mediate attachment and biofilm forming
- Produces variety of quorum sensing molecules= N-acyl homoserine lactones (AHLs)
- >regulate virulence gne expression and biofilm formation

Question 6

Pseudomonas aeruginosa , Abiotic surfaces

Paragraph 6

For 2 named pathogens, compare the molecular mechanisms by which alkaline metabolism permits their colonisation on biotic and abiotic surfaces.

Answer 6

Abiotic surfaces
- medical devices
- use alkaline metabolism: colonize, form biofilm
- > maintain pH microenvironemnt: growth and biofilm formation

Extracellular components
- Alginate
- Pel Polysaccharides
- > mediate attachment, biofilm formatio

Question 7

Conclusion- Paragraph 7

For 2 named pathogens, compare the molecular mechanisms by which alkaline metabolism permits their colonisation on biotic and abiotic surfaces.

Answer 7

Summary
- V-cholera nd P.aeruginosa use alkaline metabolism
- both colonize biotic and abiotic surfaces
- Alkaline end products: maintain pH microenvirnment : growth and colonization
- Colonize biotic surfaces: produces virulent factors : pili and exoplolysaccharides : attachment, biofilm forming
- Colonize abiotic surfaces: produce extraceullular matriz components: alginate, VPS: mediate attachmetn and biofilm forming