Lab 2 Culture of bacteria

Question 1

What is a culture medium?

Answer 1

A mixture/solution that satisfies the nutrient need of bacteria to let them reproduce

Question 2

What is the optimal temperature for pathogenic microorganisms?

Answer 2

35-37 degrees celcius

Question 3

Spore-forming bacteria have a low heat tolerance. T/F?

Answer 3

False!!

They have a high heat tolerance.

Question 4

Explain what an obligate/strict aerobic bacterium is. Give example.

Answer 4

• reproduces in presence of O2

Ex. mycobacterium tuberculosis

Question 5

Explain what a microaerophilic bacteria is. Give example.

Answer 5

They need oxygen because unable to ferment or respire anaerobically, but a high [O2] will poison them!
Decreased (5%) O2, and elevated (10%) CO2 tension.
Ex. campylobacter genus

Question 6

Explain what a facultative anaerobic bacteria is.

Give ex.

Answer 6

Can reproduce in O2, but during lack of O2 switches to fermentation!
ex. enterobacteriaceae family

Question 7

Explain what an obligate/strict anaerobic bacteria is.

Give ex.

Answer 7

O2 kills them, and they cannot neutralize H2O2 and ROS’s

• they do not contain catalses and superoxide dismutase
  ex. clostridium genus

Question 8

Explain what a paratrophic bacteria is. Give examples

Answer 8

Obtains nutrition from other living matter; parasitic.
- needs eukaryote to survive
They cannot synthesize NAD and/or ATP
ex. chlamydia, chlamydophila, rickettsia genera

Question 9

List different types of culture media:

Answer 9

• natural-artificial
• liquid-solid
• simple-complex
• selective-differentiating

Question 10

List examples of natural culture media:

Answer 10

• milk
• meat
• bile
• eggs

Question 11

What is the composition of a culture medium?

Answer 11

• water
• carbon source (polysacchs)
• nitrogen source
• salts
• trace elements
• buffers

Question 12

What is a fastidious bacteria?

Answer 12

Type of bacteria that has a complex nutritional requirement, needing materials it cannot produce such as amino acids, vitamins, etc

Question 13

What is the optimal pH for culture medium for bacteria?

Answer 13

7.2 - 7.4

• • Exceptions,
• halophile 8 - 9
• acidophile 5.4 - 6.6

Question 14

List liquid culture medias

Answer 14

• bouillon (broth)
  
  • -> has cloudish precipitate
• peptone water

Question 15

List solid culture medias:

Answer 15

• liquid bouillon WITH stiffening material (polyagarose)
• agar-agar
• test-tube: high/slant/high slant agar
• petri dish
  - -> agar plate, blood agar, chocolate agar

Question 16

List characteristics of agar-agar media:

Answer 16

• hygroscopic (absorbs 100x’s it’s weight in water)
• melts at 98 degrees
• hardens at 40-42 degrees, good for bacteria
• indigestible for bacteria, they cannot eat it!
• can be made in test tubs

Question 17

Name types of bacteria (classification):

Answer 17

• spore forming / non spore forming
• aerobic / anaerobic
• intracellular (could be facultatively IC)

Question 18

List genus of Gram + and Gram - bacteria

Answer 18

GRAM +:

• staphylococcus
• streptococcus

GRAM -:

• neisseria
• moraxella
• kingella