6: Microbial O2 Usage and Tolerance

Question 1

aerobes

Answer 1

can use gaseous O in their metabolism, including toxic O products

most fungi, protozoa, bacteria (Bacillus species, Mycobacterium tuberculosis)

Question 2

microaerophiles

Answer 2

harmed by normal atmospheric concentrations of O, but require a small amount in their metabolism

soil, water, in mammalian hosts, not directly exposed to atmosphere

Helicobacteri pylori, Borrelia burgdoferi

Question 3

facultative anaerobes

Answer 3

do not require O for metabolism, but use it when it is present

gram negative intestinal bacteria, staphylococci

Question 4

anaerobe

Answer 4

do not use O in respiration

oral and intestinal bacteria

Question 5

obligate anaerobe

Answer 5

do not process toxic O and die in its presence

oral and intestinal bacteria

Question 6

aerotolerant anaerobes

Answer 6

do not utilize O but can survive and grow to a limited extent in its presence

not harmed by O

lactobacilli, streptococci, clostridial species

Question 7

nonphotosynthetic

Answer 7

damaged by toxic oxygen products produced by contact with light