Exercise 9- Cultivation of Anaerobes

T/F. Some microbes require oxygen, some tolerate it, and some are killed by it.

True

Aerobic bacteria have enzymes which render oxygen by-products as _________________. Anaerobic bacteria lack these enzyme systems.

harmless

What are the 2 important reasons for heating the agar?

it melts the agar and drives off the oxygen (making a more anaerobic environment)

Was Micrococcus luteus a facultative anaerobe, obligate anaerobe, or obligate aerobe?

obligate aerobe

Why are sterile agar deeps heated to 100 C and then cooled to 45 C?

to liquefy the agar and then it's cooled so they are ready to be inoculated.

Was E. coli a facultative anaerobe, obligate anaerobe, or obligate aerobe?

facultative anaerobe

What is the difference between facultative anaerobe, obligate anaerobe, and obligate aerobe?

facultative anaerobe- grows with or without oxygen obligate anaerobe- only grows without oxygen obligate aerobe- only grows with oxygen

How do anaerobes produce energy? Do they need oxygen as a terminal electron acceptor?

fermentation or anaerobic respiration. No

What are the 5 groups that microbes can be divided to based on their need for oxygen?

1. Obligate or strict aerobes require oxygen for growth. 2. Obligate or strict anaerobes can't tolerate oxygen and must be cultured under conditions where oxygen is absent. 3. Facultative anaerobes can grow in the presence of oxygen or without oxygen. 4. Aerotolerant bacteria don't use oxygen as the terminal electron acceptor and are indifferent to the presence of oxygen. 5. Microaerophiles require oxygen at a lower concentration than is found in the air.

What percentage of air is oxygen? Microaerophiles require oxygen at what concentration?

20. 5-10

How do obligate or strict aerobes, that require oxygen for growth, produce energy?

aerobic respiration in which oxygen serves as the terminal electron acceptor

How do facultative anaerobes produce energy?

by aerobic respiration if oxygen is present. If oxygen isn't present, they can produce energy in other ways (fermentation)

How are anaerobes killed?

by by-products of oxygen like peroxide and superoxide radicals

Was Clostridium sporogene a facultative anaerobe, obligate anaerobe, or obligate aerobe?

obligate anaerobe