L08: Micro Lab

Question 1

Blood agar

Answer 1

• common general isolation media
• non-selective
• differential for hemolytic action

Question 2

Brain Heart Infusion (BHI) agar

Answer 2

• general purpose for growth of fastidious microbes esp. Fungi and yeast
• may see pigmentation

Question 3

MacConkey agar

Answer 3

• selective for most gram negatives
• enterics produce acid and are pigmented
• lactose fermenters are pink
• non-lactose fermenters are colorless
• bile salts may precipitate

Question 4

Mannitol salt agar

Answer 4

-turns from red to yellow if organism can ferment mannitol (ie. Staph aureus)

Question 5

Pseudomonas F agar

Answer 5

Differentiates pseudomonas aeruginosa from other pseudomonas spp. Based on fluorescein production

Question 6

Pseudomonas P agar

Answer 6

Differentiates pseudomonas aeruginosa from other pseudomonas spp. Based on pyocyanin production

Question 7

DNAase Test

Answer 7

Clearing on agar indicates degradation of DNA

-good for distinguishing coag-pos staphs

Question 8

Thioglycollate broth agar

Answer 8

Tests aerotolerance of bacteria

Question 9

3 types of growth media

Answer 9

1) all purpose
2) differential (selects for a certain property)
3) selective (inhibits other types of bacteria)