Oxygen Requirements Pg.67-69

Question 1

Oxygen is categorized in what 5 groups?

Answer 1

1. Obligate aerobes
2. Obligate anaerobes
3. Facultative anaerobes
4. Microarophiles
5. Aerotolerants

Question 2

Define obligate aerobes

Answer 2

Optimum growth occurs only in the PRESENCE of oxygen (1 atm).

Question 3

______ uses oxygen as the final electron acceptor (ETC).

Answer 3

Obligate aerobes

Question 4

Obligate anaerobes

Answer 4

Optimum growth occurs only in the absence of oxygen.

Question 5

Obligate anaerobes use ____, ____, or _____ as the final electron acceptor

Answer 5

Nitrate, sulfate, or other molecules

Question 6

Obligate anaerobes: oxygen is toxic to many anaerobes, due to:

Answer 6

Lack of detoxification enzymes, such as catalase and superoxide dismutase

Question 7

Facultative anaerobes:

Answer 7

Optimum growth occurs either in the presence or absence of oxygen.

Question 8

Facultative anaerobes: If oxygen is not available, they can use other molecules during:

Answer 8

Anaerobic respiration or fermentation.

Question 9

Microarophiles

Answer 9

Optimum growth occurs in the presence of lower oxygen levels (0.2 atms).

Question 10

Microarophiles respire aerobically using ___1.___, but respire more efficiently when the ____2.____ concentration is higher and the __3.___ concentration is lower than the usual aerobic environment.

Answer 10

1. Oxygen
2. Carbon dioxide
3. Oxygen

Question 11

Aerotolerants

Answer 11

Do not require oxygen but are not killed by it

Question 12

This procedure shows the oxygen requirements of which 3 bacteria?

Answer 12

Bacillus spizizenii (subtilis)
Clostridium sporogenes
Staphylococcus epidermidis

Question 13

Each bacteria was inoculated on what type of agar? (1)
Each bacteria was stabbed in what type of agar (2) and inoculated in what type of broth?(3)

Answer 13

1. On an agar slant
   2.stabbed into an agar tall
2. Sodium thioglycollate broth

Question 14

____________ is a reducing compound which binds free oxygen, providing a reduced environment.

Answer 14

Sodium thioglycollate

Question 15

A redox potential indicator RESAZURIN, (also included in the medium) turns what color in an oxidized environment?

Answer 15

Pink

Question 16

These cultures have been incubated for how long at what temperature?

Answer 16

48 hours at 37 degrees Celcius

Question 17

Results: is oxygen present in these 3 environments? (Slant, tall, thioglycollate)

Answer 17

Slant=yes
Tall= on top
Thioglycollate= on top

Question 18

In an ideal situation, in which media do the microbes grow the most?

Answer 18

Aerotolerant microbes grew the most in tall and thioglycollate media.

Question 19

Based on observations, indicate proper oxygen requirement category for each species.

Answer 19

Bacillus spizizenii (subtilis) = obligate aerobe
Clostridium sporogenes = obligate anaerobe
Staphylococcus epidermidis = facultative anaerobe