Bacteria with the ability to live under both aerobic and anaerobic conditions are called?

Bacteria that can thrive in both aerobic and anaerobic environments are referred to as facultative bacteria. This characteristic means that these bacteria possess the flexibility to utilize oxygen for respiration when it is available, but can also switch to anaerobic metabolism or fermentation in the absence of oxygen. This adaptability allows them to survive in diverse environments, making them quite versatile in terms of their ecological niches and roles in various biological processes.

In contrast, obligate bacteria require either oxygen (obligate aerobes) or must live in environments devoid of oxygen (obligate anaerobes), limiting their habitat possibilities. The terms "anoxic aerobic bacteria" and "non-facultative bacteria” are not standardly used in microbiology to describe groups of bacteria with the ability to adapt to both oxygen-rich and oxygen-poor conditions. Thus, the classification of these versatile organisms as facultative accurately conveys their capability to oscillate between using oxygen and relying on fermentation or anaerobic processes.