Which type of bacteria can grow best when oxygen is present, but can also survive without it?

Facultative anaerobes are the type of bacteria that can grow best in the presence of oxygen but also have the ability to survive and grow without it. This adaptability allows facultative anaerobes to utilize aerobic respiration when oxygen is available, generating more energy through this efficient metabolic pathway. In the absence of oxygen, they can switch to anaerobic processes such as fermentation to sustain themselves.

This flexibility is a significant advantage in fluctuating environments, allowing facultative anaerobes to thrive in both oxygen-rich and oxygen-poor conditions. Other types of bacteria, such as obligate anaerobes, cannot survive in the presence of oxygen at all, obligate aerobes require oxygen for their growth and cannot survive without it, and microaerophilic organisms need reduced oxygen levels to grow but are not adaptable to growth in fully aerobic or anaerobic conditions. Therefore, facultative anaerobes represent the best example of bacteria that possess this unique metabolic versatility.