Bacteria that can grow in the presence or absence of oxygen are called ___.

Bacteria that can grow in both the presence and absence of oxygen are classified as facultative anaerobes. These microorganisms have the unique ability to switch their metabolism based on the availability of oxygen. When oxygen is present, they can utilize aerobic respiration, which is more energy-efficient. Conversely, in the absence of oxygen, facultative anaerobes can switch to anaerobic respiration or fermentation processes to produce energy. This adaptability allows them to thrive in a variety of environments, including those that fluctuate between aerobic and anaerobic conditions.

Aerobes, in contrast, require oxygen for growth, while obligate anaerobes cannot tolerate oxygen at all. Microaerophiles, on the other hand, require oxygen but at lower concentrations than what is found in the atmosphere. This understanding of bacterial classification is important in various applications, including laboratory practices and animal care, as it helps inform proper handling and maintenance of cultures in research settings.