Exercise 27 Effects of Oxygen on Growth: Ignore TGYA, and Brewers agar Flashcards


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1

Tube inoculations

Tube inoculations

  1. coli : facultative anaerobe
  2. aeruginosa : obligate aerobe
  3. sporogenes : obligate anaerobe

2

Plate inoculations

Plate inoculations in air (incubator) vs anaerobe jar (gaspack)

  1. coli : facultative anaerobe
  2. aeruginosa : obligate aerobe
  3. sporogenes : obligate anaerobe

3

What is the role of oxygen in aerobic respiration?

Oxygen acts as a terminal electron acceptor during respiration.

4

What type(s) of metabolism can occur in the absence of oxygen?

In the absence of oxygen, anaerobic respiration or fermentation occurs.

5

Name two enzymes that are present in obligate aerobes but lacking in obligate anaerobes. What is the function of each enzyme?

Obligate anaerobes lack superoxide dismutase, which converts toxic superoxide to a harmless compound, and catalase, which converts toxic peroxide to oxygen.

6

Differentiate between a microaerophile and an aerotolerant organism

Microaerophiles require low amounts of oxygen for metabolism, although higher concentrations are lethal. Aerotolerant organisms can grow in oxygen but do not use it for metabolism and are thus indifferent to its presence.

7

Why is resazurin a useful media additive for the study of anaerobes?

Resazurin is an indicator for the presence of oxygen

8

Why is a GasPak anaerobic jar necessary for the cultrue of anaerobes on Brewer's anaerobic agar plates but not in tubes of fluid thioglycollate medium (FTM)?

Change the question to regular TSA instead of Brewer’s Agar: The GasPak anaerobic jar is necessary to remove the oxygen for anaerobic growth. Anaerobes grow in fluid thioglycollate medium because in the depths of the tube, the conditions are anaerobic; therefore the GasPak is unnecessary.

9

Where in the human body would you expect to find an obligate aerobe? Where would you expect to find an obligate anaerobe? Look up some examples of each and indicate where they may be found in the body?

Aerobes can be found on the human skin, e.g. Staphylococcus. Anaerobes can be found in hair follicles, e.g., Propionibacterium acnes and in the intestinal tract, e.g., Bacteroides fragilis. (knowing names of these species is not important)