Exam 1 (Ch 7 Vocab, part 2/2)

Question 1

Forms of media

Answer 1

• takes into account the needed pH, etc.

- has 3 basic forms

Question 2

3 basic forms of media

Answer 2

1. Liquid (broth)
2. Solid (plated agar)
3. Semisolid (tube)

Question 3

Liquid media

Answer 3

• contained within tube or bottle
• organism growth causes “cloudiness” or turbidity
• can be used to cultivate when sample provided is very small
• NOT used for direct isolation

Question 4

Solid media

Answer 4

• agar added to liquid media
• consistency similar to gelatin
• often used in Petri dishes
• can be used as:
  #slants
  #deeps (motility check)
• can be used for isolation

Question 5

Semisolid media

Answer 5

• same preparation as solid, with less agar (more liquid)
• consistency similar to yogurt
• so soft that it will assume the shape of its container
• used for:
  #biochemical tests
  #long-term storage of microbes
  #transport (sometimes)
• NOT media of choice for isolation

Question 6

3 categories of environmental needs

Answer 6

1. Temperature
2. Atmosphere
3. Humidity

Question 7

Psychrophiles

Answer 7

• about 0 - 20 degrees C
• live in extremely cold regions of the world
  #Arctic
  #Antarctic
• NOT associated with human disease (can’t survive in vivo)

Question 8

Thermophiles

Answer 8

• about 40 - 90 degrees C
• live in hot environments
  #hot springs
  #compost heaps
• NOT associated with human disease (can’t survive in vivo)

Question 9

Mesophiles

Answer 9

• about 20 - 40 degrees C
• are associated with human disease (can grow at body temperature)
• labs use incubators and heat blocks to mimic body temperature

Question 10

2 special cases in temperature

Answer 10

1. Yersinia

2. Campylobacter

Question 11

Yersinia

Answer 11

• intestinal pathogen
• grows best at 22 - 25 degrees C
• leave plate at room temperature

Question 12

Campylobacter

Answer 12

grows best at 42 degrees C plus CO2

Question 13

4 types of atmospheric environments

Answer 13

1. Ambient air
2. CO2
3. Microaerophilic
4. Anaerobic

Question 14

Ambient air requirements

Answer 14

- mixture of various gases
     # 21% O2
     # 0.03% CO2
     # 78% N
     # mixture of other

Question 15

CO2 requirements

Answer 15

• incubator with gas cylinder
• candle jar
• gas pack

Question 16

Microaerophilic requirements

Answer 16

- approximately:
     # 5% O2
     # 10% CO2
     # 85% N
- O2 greater than 6% would inhibit or harm these organisms

Question 17

Example species that requires microaerophilic atmosphere

Answer 17

Campylobacter species

Question 18

Anaerobic requirements

Answer 18

• harmed by presence of O2
• in lab, environment produced chemically or O2-proof chamber (anaerobic jar)
• approximately:
  # 85% N
  # 10% H2
  # 5% CO2

Question 19

Example species that requires anaerobic atmosphere

Answer 19

Bacteroides fragilis

Question 20

Humidity

Answer 20

• microorganisms must have humidity to survive
• approximately 70% humidity level
• incubators usually have:
  #built-in water reservoir
  #humidity regulator
• may have to manually add water to older units

Question 21

Inoculation

Answer 21

the act of transferring the specimen to a growth media

Question 22

Pre-inoculation

Answer 22

• ensure correct specimen received with proper label
• verify which media is needed
• is screening (Gram stain, wet prep, etc.) also ordered or needed?

Question 23

ugh just read the rest of the powerpoint pls

Answer 23

okay :’(