What defines an obligate aerobe?

An obligate aerobe is defined by its requirement for oxygen to survive. These microorganisms rely on oxygen for their metabolic processes, specifically for cellular respiration, which allows them to efficiently generate energy. In environments where oxygen is absent, obligate aerobes are unable to sustain their growth or reproduce, leading to death. This contrasts sharply with other types of bacteria, such as facultative anaerobes or obligate anaerobes, which can either survive without oxygen or thrive only in its absence, respectively. Therefore, the defining characteristic of obligate aerobes is their absolute need for oxygen, making the choice that states they require oxygen for survival the correct one.