Bacteria may be grouped based on oxygen requirement. Recall that obligate aerobic bacteria require oxygen and do not use fermentation to provide energy to the cells.
Aerobes may be subdivided into:
- Obligate: requiring oxygen
- Microaerophile: growing best in reduced oxygen
- Capnophile: requiring increased CO2 for growth
Some overlap may occur, as most aerobes may also be considered facultative anaerobes—they can grow in the presence or absence of oxygen.
Anaerobes are quite different and may be divided into two main groups: obligate and facultative.3 Oxygen is toxic when present in the amounts described below:
- Obligate anaerobes use fermentation and organic compounds to provide energy. Obligate anaerobes may be subdivided into:
- Strict obligate anaerobes: will not survive if more than 0.5% oxygen is present
- Moderate obligate anaerobes: will grow in the presence of 2 to 8% oxygen
- Facultative anaerobes can grow in the presence or absence of oxygen.
3. Turgeon ML, ed. Clinical Laboratory Science: Concepts, Procedures, and Clinical Applications. 9th ed. Elsevier. 2022.
