Obligate aerobe

Aerobic and anaerobic bacteria can be identified by growing them in liquid culture:
1. Obligate aerobe
2. Obligate anaerobe
3. Facultative anaerobic organism (continuum with "Facultative aerobic organism")
4. Microaerophile
5. Aerotolerant

An obligate aerobe is an aerobic organism that requires oxygen to grow. Through cellular respiration, these organisms use oxygen to oxidize substances, like sugars or fats, in order to obtain energy. During respiration, they use oxygen as the terminal electron acceptor. They have the advantage of yielding more energy than obligate anaerobes, but face high levels of oxidative stress.

Examples of obligate aerobic bacteria: Nocardia (Gram-positive), Mycobacterium tuberculosis (acid-fast), and Bacillus (Gram-positive).