What type of microorganisms require oxygen for growth?

The correct choice is aerobic microorganisms, which are defined by their requirement for oxygen to grow. These organisms utilize oxygen in their metabolic processes, allowing them to convert nutrients into energy through cellular respiration, which efficiently generates ATP, the energy currency of cells.

Aerobic microorganisms thrive in environments where oxygen is present, making them integral to various ecosystems and important for processes such as decomposition and nutrient cycling. The presence of oxygen supports their growth and reproduction, facilitating various biochemical reactions that sustain their life cycle. Without adequate oxygen, these microorganisms cannot perform their essential functions.

On the other hand, anaerobic microorganisms do not require oxygen for growth and may even find oxygen toxic. Facultative anaerobes can grow in both the presence and absence of oxygen, which makes them versatile but not strictly dependent on oxygen like aerobes. Pathogenic microorganisms can be a broader category, as they may include both aerobic and anaerobic types, depending on the specific microorganism and the type of infection they cause.