Table 1.
Characterization of microorganisms in relation to O2 metabolism
| Organisms | Aerobic growth |
Low-affinity oxidase |
Microaerobic growth |
High-affinity oxidase |
ROS defence |
Anaerobic growth |
Representative species |
|---|---|---|---|---|---|---|---|
| Obligate aerobes | + | + | − | − | + | − | Mycobacterium leprae |
| Microaerophiles | + | − | + | + | + | − | Helicobacter pylori |
| Facultative anaerobes* | + | + | + | + | + | + | Escherichia coli |
| Nanaerobes | + | − | + | + | + | + | Bacteroides fragilis |
| Aerotolerant anaerobes | − | − | − | − | + | + | Streptococcus pneumoniae |
| Obligate anaerobes‡ | − | − | − | − | − | + | Clostridium tetani |
ROS, reactive oxygen species.
*
Not all facultative anaerobes have high-affinity oxidases or grow microaerobically.
‡
Many obligate anaerobes tolerate transient or low levels of O2.